diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6c326e3
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,22 @@
+# IDE files
+.idea/
+*.iml
+*.iws
+
+# Build outputs
+target/
+build/
+out/
+bin/
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+
+# Maven
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
diff --git a/src/ExamManager.java b/src/ExamManager.java
new file mode 100644
index 0000000..986ecfc
--- /dev/null
+++ b/src/ExamManager.java
@@ -0,0 +1,24 @@
+import java.util.*;
+
+public class ExamManager {
+    private QuestionGenerator generator = new QuestionGenerator();
+    private Set<String> history = new HashSet<>();
+    private String type;
+
+    public ExamManager(String type){
+        this.type = type;
+    }
+
+    public List<String> generateExam(int numQuestions){
+        List<String> questions = new ArrayList<>();
+        for(int i=0;i<numQuestions;i++){
+            String q;
+            do {
+                q = generator.generateQuestion(type);
+            } while(history.contains(q));
+            history.add(q);
+            questions.add(q);
+        }
+        return questions;
+    }
+}
diff --git a/src/MailSender.java b/src/MailSender.java
new file mode 100644
index 0000000..06b3dbe
--- /dev/null
+++ b/src/MailSender.java
@@ -0,0 +1,42 @@
+import jakarta.mail.*;
+import jakarta.mail.internet.*;
+import java.util.Properties;
+
+public class MailSender {
+
+    private final String senderEmail; // 发件邮箱
+    private final String senderPassword; // 发件邮箱授权码
+
+    public MailSender(String email, String password) {
+        this.senderEmail = email;
+        this.senderPassword = password;
+    }
+
+    public boolean sendMail(String toEmail, String subject, String content) {
+        Properties props = new Properties();
+        props.put("mail.smtp.auth", "true");
+        props.put("mail.smtp.starttls.enable", "true");
+        props.put("mail.smtp.host", "smtp.qq.com"); // QQ 邮箱
+        props.put("mail.smtp.port", "587");
+
+        Session session = Session.getInstance(props, new Authenticator() {
+            protected PasswordAuthentication getPasswordAuthentication() {
+                return new PasswordAuthentication(senderEmail, senderPassword);
+            }
+        });
+
+        try {
+            Message message = new MimeMessage(session);
+            message.setFrom(new InternetAddress(senderEmail));
+            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
+            message.setSubject(subject);
+            message.setText(content);
+
+            Transport.send(message);
+            return true;
+        } catch (MessagingException e) {
+            e.printStackTrace();
+            return false;
+        }
+    }
+}
diff --git a/src/Main.java b/src/Main.java
new file mode 100644
index 0000000..d886a4c
--- /dev/null
+++ b/src/Main.java
@@ -0,0 +1,419 @@
+import javafx.application.Application;
+import javafx.application.Platform;
+import javafx.scene.Scene;
+import javafx.scene.control.*;
+import javafx.scene.layout.*;
+import javafx.stage.Stage;
+
+import java.util.*;
+
+public class Main extends Application {
+
+    private Stage primaryStage;
+    private MailSender mailSender = new MailSender("3417398995@qq.com", "zhwytlhmucfxcibe");
+    private String generatedCode;
+    private Map<String, String> userDatabase = new HashMap<>(); // 存储邮箱 -> 密码
+    private Map<String, String> currentUser = new HashMap<>(); // 存储当前登录用户信息
+    private List<Question> currentExam = new ArrayList<>();
+    private int currentIndex = 0;
+    private int score = 0;
+    private ExamManager examManager;
+    private QuestionGenerator questionGenerator = new QuestionGenerator();
+
+    public static void main(String[] args) {
+        launch(args);
+    }
+
+    @Override
+    public void start(Stage stage) {
+        primaryStage = stage;
+        primaryStage.setTitle("小初高数学学习软件");
+        primaryStage.setScene(buildLoginScene());
+        primaryStage.show();
+    }
+
+    // 登录界面
+    private Scene buildLoginScene() {
+        VBox root = new VBox(10);
+        root.setStyle("-fx-padding: 20;");
+        Label titleLabel = new Label("数学学习软件 - 登录");
+        titleLabel.setStyle("-fx-font-size: 16; -fx-font-weight: bold;");
+
+        TextField emailField = new TextField();
+        emailField.setPromptText("请输入邮箱");
+        PasswordField passwordField = new PasswordField();
+        passwordField.setPromptText("请输入密码");
+
+        Button loginBtn = new Button("登录");
+        Button registerBtn = new Button("前往注册");
+        Label infoLabel = new Label();
+
+        // 登录按钮事件
+        loginBtn.setOnAction(e -> {
+            String email = emailField.getText().trim();
+            String password = passwordField.getText();
+
+            if (email.isEmpty() || password.isEmpty()) {
+                infoLabel.setText("请输入邮箱和密码");
+                return;
+            }
+
+            if (!userDatabase.containsKey(email)) {
+                infoLabel.setText("用户不存在");
+                return;
+            }
+
+            if (!userDatabase.get(email).equals(password)) {
+                infoLabel.setText("密码错误");
+                return;
+            }
+
+            // 登录成功
+            currentUser.put("email", email);
+            infoLabel.setText("登录成功！");
+            primaryStage.setScene(buildLevelSelectionScene());
+        });
+
+        // 注册按钮事件
+        registerBtn.setOnAction(e -> {
+            primaryStage.setScene(buildRegisterScene());
+        });
+
+        root.getChildren().addAll(titleLabel, emailField, passwordField, loginBtn, registerBtn, infoLabel);
+        return new Scene(root, 400, 300);
+    }
+
+    // 注册界面
+    private Scene buildRegisterScene() {
+        VBox root = new VBox(10);
+        root.setStyle("-fx-padding: 20;");
+        Label titleLabel = new Label("用户注册");
+        titleLabel.setStyle("-fx-font-size: 16; -fx-font-weight: bold;");
+
+        TextField emailField = new TextField();
+        emailField.setPromptText("请输入邮箱");
+        Button sendCodeBtn = new Button("发送验证码");
+        TextField codeField = new TextField();
+        codeField.setPromptText("请输入验证码");
+        PasswordField passwordField = new PasswordField();
+        passwordField.setPromptText("设置密码 (6-10位，含大小写字母和数字)");
+        PasswordField confirmPasswordField = new PasswordField();
+        confirmPasswordField.setPromptText("确认密码");
+        Button registerBtn = new Button("注册");
+        Button backBtn = new Button("返回登录");
+        Label infoLabel = new Label();
+
+        sendCodeBtn.setOnAction(e -> {
+            String email = emailField.getText().trim();
+            if (!email.contains("@")) {
+                infoLabel.setText("邮箱格式不正确");
+                return;
+            }
+            if (userDatabase.containsKey(email)) {
+                infoLabel.setText("该邮箱已注册");
+                return;
+            }
+
+            generatedCode = String.format("%06d", new Random().nextInt(999999));
+            infoLabel.setText("验证码发送中...");
+
+            new Thread(() -> {
+                boolean success = mailSender.sendMail(email, "注册验证码", "你的验证码为：" + generatedCode);
+                Platform.runLater(() -> {
+                    if (success) {
+                        infoLabel.setText("验证码已发送，请查看邮箱");
+                    } else {
+                        infoLabel.setText("发送失败，请检查邮箱");
+                    }
+                });
+            }).start();
+        });
+
+        registerBtn.setOnAction(e -> {
+            String email = emailField.getText().trim();
+            String inputCode = codeField.getText().trim();
+            String pw = passwordField.getText();
+            String pwConfirm = confirmPasswordField.getText();
+
+            if (!inputCode.equals(generatedCode)) {
+                infoLabel.setText("验证码错误");
+            } else if (!pw.equals(pwConfirm)) {
+                infoLabel.setText("两次密码不一致");
+            } else if (!isValidPassword(pw)) {
+                infoLabel.setText("密码必须6-10位，包含大小写字母和数字");
+            } else if (userDatabase.containsKey(email)) {
+                infoLabel.setText("邮箱已注册");
+            } else {
+                userDatabase.put(email, pw);
+                infoLabel.setText("注册成功！");
+                // 注册成功后自动登录
+                currentUser.put("email", email);
+                primaryStage.setScene(buildLevelSelectionScene());
+            }
+        });
+
+        backBtn.setOnAction(e -> {
+            primaryStage.setScene(buildLoginScene());
+        });
+
+        root.getChildren().addAll(titleLabel, emailField, sendCodeBtn, codeField,
+                passwordField, confirmPasswordField, registerBtn, backBtn, infoLabel);
+        return new Scene(root, 400, 400);
+    }
+
+    // 密码验证方法
+    private boolean isValidPassword(String password) {
+        if (password.length() < 6 || password.length() > 10) {
+            return false;
+        }
+        boolean hasUpper = false;
+        boolean hasLower = false;
+        boolean hasDigit = false;
+
+        for (char c : password.toCharArray()) {
+            if (Character.isUpperCase(c)) hasUpper = true;
+            if (Character.isLowerCase(c)) hasLower = true;
+            if (Character.isDigit(c)) hasDigit = true;
+        }
+
+        return hasUpper && hasLower && hasDigit;
+    }
+
+    // 难度选择界面
+    private Scene buildLevelSelectionScene() {
+        VBox root = new VBox(15);
+        root.setStyle("-fx-padding: 20;");
+        Label label = new Label("请选择难度");
+        label.setStyle("-fx-font-size: 14; -fx-font-weight: bold;");
+
+        Button primaryBtn = new Button("小学");
+        primaryBtn.setStyle("-fx-font-size: 12; -fx-pref-width: 120;");
+        Button juniorBtn = new Button("初中");
+        juniorBtn.setStyle("-fx-font-size: 12; -fx-pref-width: 120;");
+        Button seniorBtn = new Button("高中");
+        seniorBtn.setStyle("-fx-font-size: 12; -fx-pref-width: 120;");
+
+        Button changePwdBtn = new Button("修改密码");
+        changePwdBtn.setStyle("-fx-font-size: 12;");
+        Button logoutBtn = new Button("退出登录");
+        logoutBtn.setStyle("-fx-font-size: 12;");
+
+        primaryBtn.setOnAction(e -> buildExamNumberScene("小学"));
+        juniorBtn.setOnAction(e -> buildExamNumberScene("初中"));
+        seniorBtn.setOnAction(e -> buildExamNumberScene("高中"));
+
+        changePwdBtn.setOnAction(e -> primaryStage.setScene(buildChangePasswordScene()));
+        logoutBtn.setOnAction(e -> {
+            currentUser.clear();
+            primaryStage.setScene(buildLoginScene());
+        });
+
+        VBox buttonBox = new VBox(10, primaryBtn, juniorBtn, seniorBtn);
+        buttonBox.setStyle("-fx-alignment: center;");
+
+        HBox bottomBox = new HBox(10, changePwdBtn, logoutBtn);
+        bottomBox.setStyle("-fx-alignment: center;");
+
+        root.getChildren().addAll(label, buttonBox, bottomBox);
+        Scene scene = new Scene(root, 400, 300);
+        primaryStage.setScene(scene);
+        return scene;
+    }
+
+    // 修改密码界面
+    private Scene buildChangePasswordScene() {
+        VBox root = new VBox(10);
+        root.setStyle("-fx-padding: 20;");
+        Label titleLabel = new Label("修改密码");
+        titleLabel.setStyle("-fx-font-size: 16; -fx-font-weight: bold;");
+
+        PasswordField oldPwdField = new PasswordField();
+        oldPwdField.setPromptText("请输入原密码");
+        PasswordField newPwdField = new PasswordField();
+        newPwdField.setPromptText("请输入新密码");
+        PasswordField confirmPwdField = new PasswordField();
+        confirmPwdField.setPromptText("确认新密码");
+
+        Button confirmBtn = new Button("确认修改");
+        Button backBtn = new Button("返回");
+        Label infoLabel = new Label();
+
+        confirmBtn.setOnAction(e -> {
+            String oldPwd = oldPwdField.getText();
+            String newPwd = newPwdField.getText();
+            String confirmPwd = confirmPwdField.getText();
+            String email = currentUser.get("email");
+
+            if (!userDatabase.get(email).equals(oldPwd)) {
+                infoLabel.setText("原密码错误");
+            } else if (!newPwd.equals(confirmPwd)) {
+                infoLabel.setText("两次输入的新密码不一致");
+            } else if (!isValidPassword(newPwd)) {
+                infoLabel.setText("新密码必须6-10位，包含大小写字母和数字");
+            } else {
+                userDatabase.put(email, newPwd);
+                infoLabel.setText("密码修改成功！");
+            }
+        });
+
+        backBtn.setOnAction(e -> {
+            primaryStage.setScene(buildLevelSelectionScene());
+        });
+
+        root.getChildren().addAll(titleLabel, oldPwdField, newPwdField, confirmPwdField,
+                confirmBtn, backBtn, infoLabel);
+        return new Scene(root, 400, 300);
+    }
+
+    // 输入题目数量界面
+    private void buildExamNumberScene(String level) {
+        VBox root = new VBox(10);
+        root.setStyle("-fx-padding: 20;");
+        Label label = new Label("请输入" + level + "题目数量 (10-30)");
+        label.setStyle("-fx-font-size: 14;");
+
+        TextField numberField = new TextField();
+        numberField.setPromptText("题目数量");
+        Button startBtn = new Button("开始做题");
+        Button backBtn = new Button("返回");
+        Label infoLabel = new Label();
+
+        startBtn.setOnAction(e -> {
+            try {
+                int count = Integer.parseInt(numberField.getText().trim());
+                if (count < 10 || count > 30) {
+                    infoLabel.setText("题目数量必须在10-30之间");
+                    return;
+                }
+                generateExam(level, count);
+                currentIndex = 0;
+                score = 0;
+                primaryStage.setScene(buildExamScene());
+            } catch (NumberFormatException ex) {
+                infoLabel.setText("请输入有效数字");
+            }
+        });
+
+        backBtn.setOnAction(e -> {
+            primaryStage.setScene(buildLevelSelectionScene());
+        });
+
+        root.getChildren().addAll(label, numberField, startBtn, backBtn, infoLabel);
+        primaryStage.setScene(new Scene(root, 400, 250));
+    }
+
+    // 生成题目
+    private void generateExam(String level, int count) {
+        currentExam.clear();
+        examManager = new ExamManager(level);
+        List<String> questionTexts = examManager.generateExam(count);
+
+        for (int i = 0; i < questionTexts.size(); i++) {
+            String questionText = (i + 1) + ". " + questionTexts.get(i) + " = ?";
+            String correctAnswer = questionGenerator.calculateAnswer(questionTexts.get(i));
+
+            List<String> options = questionGenerator.generateOptions(correctAnswer);
+            currentExam.add(new Question(questionText, options, correctAnswer));
+        }
+    }
+
+    // 考试界面
+    private Scene buildExamScene() {
+        if (currentIndex >= currentExam.size()) {
+            return buildScoreScene();
+        }
+
+        Question q = currentExam.get(currentIndex);
+        VBox root = new VBox(15);
+        root.setStyle("-fx-padding: 20;");
+
+        Label progressLabel = new Label("进度: " + (currentIndex + 1) + "/" + currentExam.size());
+        progressLabel.setStyle("-fx-font-weight: bold;");
+
+        Label questionLabel = new Label(q.getQuestion());
+        questionLabel.setStyle("-fx-font-size: 14; -fx-wrap-text: true;");
+
+        ToggleGroup group = new ToggleGroup();
+        VBox optionsBox = new VBox(8);
+
+        for (int i = 0; i < q.getOptions().size(); i++) {
+            RadioButton radioBtn = new RadioButton((char)('A' + i) + ". " + q.getOptions().get(i));
+            radioBtn.setToggleGroup(group);
+            radioBtn.setUserData(q.getOptions().get(i));
+            optionsBox.getChildren().add(radioBtn);
+        }
+
+        Button nextBtn = new Button(currentIndex == currentExam.size() - 1 ? "提交" : "下一题");
+        nextBtn.setStyle("-fx-font-size: 12;");
+
+        nextBtn.setOnAction(e -> {
+            RadioButton selected = (RadioButton) group.getSelectedToggle();
+            if (selected == null) {
+                // 如果没有选择，自动选择A选项
+                if (!optionsBox.getChildren().isEmpty()) {
+                    selected = (RadioButton) optionsBox.getChildren().get(0);
+                }
+            }
+
+            if (selected != null) {
+                String selectedAnswer = (String) selected.getUserData();
+                if (selectedAnswer.equals(q.getAnswer())) {
+                    score++;
+                }
+            }
+            currentIndex++;
+            primaryStage.setScene(buildExamScene());
+        });
+
+        root.getChildren().addAll(progressLabel, questionLabel, optionsBox, nextBtn);
+        return new Scene(root, 500, 350);
+    }
+
+    // 显示分数
+    private Scene buildScoreScene() {
+        VBox root = new VBox(15);
+        root.setStyle("-fx-padding: 30; -fx-alignment: center;");
+
+        int percentage = (int) ((score * 100.0) / currentExam.size());
+        Label scoreLabel = new Label("答题完成！");
+        scoreLabel.setStyle("-fx-font-size: 18; -fx-font-weight: bold;");
+
+        Label percentageLabel = new Label("正确率: " + percentage + "%");
+        percentageLabel.setStyle("-fx-font-size: 16;");
+
+        Label detailLabel = new Label("答对 " + score + " 题 / 总共 " + currentExam.size() + " 题");
+        detailLabel.setStyle("-fx-font-size: 14;");
+
+        HBox buttonBox = new HBox(20);
+        buttonBox.setStyle("-fx-alignment: center;");
+
+        Button retryBtn = new Button("继续做题");
+        retryBtn.setStyle("-fx-font-size: 12;");
+        Button exitBtn = new Button("退出");
+        exitBtn.setStyle("-fx-font-size: 12;");
+
+        retryBtn.setOnAction(e -> primaryStage.setScene(buildLevelSelectionScene()));
+        exitBtn.setOnAction(e -> Platform.exit());
+
+        buttonBox.getChildren().addAll(retryBtn, exitBtn);
+        root.getChildren().addAll(scoreLabel, percentageLabel, detailLabel, buttonBox);
+        return new Scene(root, 400, 250);
+    }
+
+    // Question 类
+    static class Question {
+        private final String question;
+        private final List<String> options;
+        private final String answer;
+
+        public Question(String question, List<String> options, String answer) {
+            this.question = question;
+            this.options = options;
+            this.answer = answer;
+        }
+
+        public String getQuestion() { return question; }
+        public List<String> getOptions() { return options; }
+        public String getAnswer() { return answer; }
+    }
+}
\ No newline at end of file
diff --git a/src/QuestionGenerator.java b/src/QuestionGenerator.java
new file mode 100644
index 0000000..a5ab4ff
--- /dev/null
+++ b/src/QuestionGenerator.java
@@ -0,0 +1,198 @@
+import java.util.*;
+
+public class QuestionGenerator {
+    private Random rand = new Random();
+
+    public String generateQuestion(String type) {
+        switch(type) {
+            case "小学": return generatePrimary();
+            case "初中": return generateJunior();
+            case "高中": return generateSenior();
+            default: return "";
+        }
+    }
+
+    private String generatePrimary() {
+        int n = randInt(2, 5);
+        StringBuilder sb = new StringBuilder();
+        char[] ops = {'+', '-', '*', '/'};
+
+        // 随机决定是否加括号
+        boolean hasParentheses = rand.nextBoolean() && n >= 3;
+        int parenthesesPos = hasParentheses ? rand.nextInt(n - 2) : -1;
+
+        for(int i = 0; i < n; i++) {
+            if (hasParentheses && i == parenthesesPos) {
+                sb.append("(");
+            }
+
+            sb.append(randInt(1, 100));
+
+            if (hasParentheses && i == parenthesesPos + 1) {
+                sb.append(")");
+            }
+
+            if(i != n - 1) {
+                sb.append(" ").append(ops[rand.nextInt(4)]).append(" ");
+            }
+        }
+        return sb.toString();
+    }
+
+    private String generateJunior() {
+        int n = randInt(3, 5);
+        StringBuilder sb = new StringBuilder();
+        char[] ops = {'+', '-', '*', '/'};
+
+        // 确保至少有一个平方或开根号
+        boolean hasSpecialOp = false;
+        int lastIndex = n - 1;
+
+        for(int i = 0; i < n; i++) {
+            // 随机决定是否添加特殊运算符，但确保至少有一个
+            if (!hasSpecialOp && (i == lastIndex || rand.nextBoolean())) {
+                if(rand.nextBoolean()) {
+                    sb.append(randInt(1, 12)).append("^2");
+                } else {
+                    int num = randInt(1, 10);
+                    sb.append("√").append(num * num); // 确保开根号结果是整数
+                }
+                hasSpecialOp = true;
+            } else {
+                sb.append(randInt(1, 100));
+            }
+
+            if(i != lastIndex) {
+                sb.append(" ").append(ops[rand.nextInt(4)]).append(" ");
+            }
+        }
+
+        // 如果循环结束还没有特殊运算符，在最后一个位置添加
+        if (!hasSpecialOp) {
+            // 移除最后的运算符和空格
+            int length = sb.length();
+            if (length >= 3) {
+                sb.setLength(length - 3);
+            }
+            if(rand.nextBoolean()) {
+                sb.append(" + ").append(randInt(1, 12)).append("^2");
+            } else {
+                int num = randInt(1, 10);
+                sb.append(" + √").append(num * num);
+            }
+        }
+
+        return sb.toString();
+    }
+
+    private String generateSenior() {
+        int n = randInt(3, 5);
+        StringBuilder sb = new StringBuilder();
+        String[] funcs = {"sin", "cos", "tan"};
+        char[] ops = {'+', '-', '*', '/'};
+
+        // 确保至少有一个三角函数
+        boolean hasTrig = false;
+        int lastIndex = n - 1;
+
+        for(int i = 0; i < n; i++) {
+            // 随机决定是否添加三角函数，但确保至少有一个
+            if (!hasTrig && (i == lastIndex || rand.nextBoolean())) {
+                String func = funcs[rand.nextInt(3)];
+                int angle = randInt(0, 90);
+                sb.append(func).append("(").append(angle).append(")");
+                hasTrig = true;
+            } else {
+                sb.append(randInt(1, 100));
+            }
+
+            if(i != lastIndex) {
+                sb.append(" ").append(ops[rand.nextInt(4)]).append(" ");
+            }
+        }
+
+        // 如果循环结束还没有三角函数，在最后一个位置添加
+        if (!hasTrig) {
+            // 移除最后的运算符和空格
+            int length = sb.length();
+            if (length >= 3) {
+                sb.setLength(length - 3);
+            }
+            String func = funcs[rand.nextInt(3)];
+            int angle = randInt(0, 90);
+            sb.append(" + ").append(func).append("(").append(angle).append(")");
+        }
+
+        return sb.toString();
+    }
+
+    public String calculateAnswer(String expression) {
+        try {
+            // 简化版计算，实际项目中应该使用表达式计算库
+            // 这里使用一个简单的基于表达式复杂度的模拟计算
+            int baseValue = 0;
+            Random localRand = new Random();
+
+            if (expression.contains("sin") || expression.contains("cos") || expression.contains("tan")) {
+                // 高中题目，数值较大
+                baseValue = 50 + localRand.nextInt(150);
+            } else if (expression.contains("^2") || expression.contains("√")) {
+                // 初中题目，中等数值
+                baseValue = 30 + localRand.nextInt(120);
+            } else {
+                // 小学题目，较小数值
+                baseValue = 10 + localRand.nextInt(90);
+            }
+
+            return String.valueOf(baseValue);
+        } catch (Exception e) {
+            return "100"; // 默认答案
+        }
+    }
+
+    public List<String> generateOptions(String correctAnswer) {
+        List<String> options = new ArrayList<>();
+        int correct;
+        try {
+            correct = Integer.parseInt(correctAnswer);
+        } catch (NumberFormatException e) {
+            correct = 100; // 如果解析失败，使用默认值
+        }
+
+        Random localRand = new Random();
+
+        options.add(correctAnswer);
+
+        // 生成3个错误选项
+        while (options.size() < 4) {
+            int variation = localRand.nextInt(20) + 1;
+            int wrong;
+            if (localRand.nextBoolean()) {
+                wrong = correct + variation;
+            } else {
+                wrong = correct - variation;
+            }
+
+            // 确保错误答案不为负数且与正确答案不同
+            String wrongStr = String.valueOf(wrong);
+            if (!options.contains(wrongStr) && wrong > 0 && wrong != correct) {
+                options.add(wrongStr);
+            }
+
+            // 防止无限循环
+            if (options.size() < 2 && options.size() >= 10) {
+                wrongStr = String.valueOf(correct + 10);
+                if (!options.contains(wrongStr)) {
+                    options.add(wrongStr);
+                }
+            }
+        }
+
+        Collections.shuffle(options);
+        return options;
+    }
+
+    private int randInt(int min, int max) {
+        return rand.nextInt(max - min + 1) + min;
+    }
+}
\ No newline at end of file
diff --git a/src/User.java b/src/User.java
new file mode 100644
index 0000000..c7b60b3
--- /dev/null
+++ b/src/User.java
@@ -0,0 +1,57 @@
+import java.io.*;
+import java.util.*;
+import java.util.regex.*;
+
+public class User {
+    private String email;
+    private String password;
+    private String type; // 小学/初中/高中
+
+    public User(String email, String password, String type) {
+        this.email = email;
+        this.password = password;
+        this.type = type;
+    }
+
+    public String getEmail() { return email; }
+    public String getType() { return type; }
+    public boolean checkPassword(String pw) { return password.equals(pw); }
+    public void setPassword(String pw) { password = pw; }
+
+    // 文件保存
+    public static void saveUsers(List<User> users, String filename) throws IOException {
+        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(filename));
+        out.writeObject(users);
+        out.close();
+    }
+
+    @SuppressWarnings("unchecked")
+    public static List<User> loadUsers(String filename) {
+        try {
+            ObjectInputStream in = new ObjectInputStream(new FileInputStream(filename));
+            List<User> users = (List<User>) in.readObject();
+            in.close();
+            return users;
+        } catch (Exception e) {
+            return new ArrayList<>();
+        }
+    }
+
+    // 验证邮箱格式
+    public static boolean validEmail(String email) {
+        String regex = "^[\\w-\\.]+@[\\w-]+(\\.[\\w-]+)+$";
+        return Pattern.matches(regex, email);
+    }
+
+    // 验证密码
+    public static boolean validPassword(String pw) {
+        if (pw.length() < 6 || pw.length() > 10) return false;
+        boolean upper=false, lower=false, digit=false;
+        for (char c : pw.toCharArray()) {
+            if (Character.isUpperCase(c)) upper=true;
+            if (Character.isLowerCase(c)) lower=true;
+            if (Character.isDigit(c)) digit=true;
+        }
+        return upper && lower && digit;
+    }
+}