diff --git a/src/MathQuestion.java b/src/MathQuestion.java
new file mode 100644
index 0000000..9b2bf62
--- /dev/null
+++ b/src/MathQuestion.java
@@ -0,0 +1,39 @@
+/**
+ * 数学题目类
+ * 存储题目表达式和答案
+ */
+public class MathQuestion {
+    private String expression;
+    private String answer;
+    
+    public MathQuestion(String expression, String answer) {
+        this.expression = expression;
+        this.answer = answer;
+    }
+    
+    public String getExpression() {
+        return expression;
+    }
+    
+    public String getAnswer() {
+        return answer;
+    }
+    
+    @Override
+    public String toString() {
+        return expression;
+    }
+    
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        MathQuestion that = (MathQuestion) obj;
+        return expression.equals(that.expression);
+    }
+    
+    @Override
+    public int hashCode() {
+        return expression.hashCode();
+    }
+}
diff --git a/src/MathQuestionGenerator.java b/src/MathQuestionGenerator.java
new file mode 100644
index 0000000..502bff8
--- /dev/null
+++ b/src/MathQuestionGenerator.java
@@ -0,0 +1,148 @@
+import java.util.*;
+
+/**
+ * 数学题目生成器
+ * 根据不同难度要求生成数学题目
+ */
+public class MathQuestionGenerator {
+    private Random random;
+    private String[] operators = {"+", "-", "*", "/"};
+    private String[] trigFunctions = {"sin", "cos", "tan"};
+    
+    public MathQuestionGenerator() {
+        this.random = new Random();
+    }
+    
+    /**
+     * 根据账户类型生成题目
+     * @param accountType 账户类型（小学、初中、高中）
+     * @param count 生成题目数量
+     * @return 题目列表
+     */
+    public List<MathQuestion> generateQuestions(String accountType, int count) {
+        List<MathQuestion> questions = new ArrayList<>();
+        
+        for (int i = 0; i < count; i++) {
+            MathQuestion question;
+            switch (accountType) {
+                case "小学":
+                    question = generateElementaryQuestion();
+                    break;
+                case "初中":
+                    question = generateMiddleSchoolQuestion();
+                    break;
+                case "高中":
+                    question = generateHighSchoolQuestion();
+                    break;
+                default:
+                    question = generateElementaryQuestion();
+            }
+            questions.add(question);
+        }
+        
+        return questions;
+    }
+    
+    /**
+     * 生成小学题目：只能有+、-、*、/和()
+     */
+    private MathQuestion generateElementaryQuestion() {
+        int operatorCount = random.nextInt(4) + 1; // 1-4个操作符
+        List<Integer> numbers = new ArrayList<>();
+        List<String> ops = new ArrayList<>();
+        
+        // 生成数字（1-100）
+        for (int i = 0; i <= operatorCount; i++) {
+            numbers.add(random.nextInt(100) + 1);
+        }
+        
+        // 生成操作符
+        for (int i = 0; i < operatorCount; i++) {
+            ops.add(operators[random.nextInt(operators.length)]);
+        }
+        
+        // 构建表达式
+        StringBuilder expression = new StringBuilder();
+        expression.append(numbers.get(0));
+        
+        for (int i = 0; i < operatorCount; i++) {
+            expression.append(" ").append(ops.get(i)).append(" ").append(numbers.get(i + 1));
+        }
+        
+        // 可能添加括号
+        if (operatorCount >= 2 && random.nextBoolean()) {
+            expression = addParentheses(expression.toString());
+        }
+        
+        return new MathQuestion(expression.toString(), "计算结果");
+    }
+    
+    /**
+     * 生成初中题目：至少有一个平方或开根号运算符
+     */
+    private MathQuestion generateMiddleSchoolQuestion() {
+        StringBuilder expression = new StringBuilder();
+        
+        // 基础部分
+        int num1 = random.nextInt(50) + 1;
+        String op = operators[random.nextInt(operators.length)];
+        
+        expression.append(num1).append(" ").append(op).append(" ");
+        
+        // 添加平方或开根号
+        if (random.nextBoolean()) {
+            // 添加平方
+            int baseNum = random.nextInt(20) + 1;
+            expression.append(baseNum).append("²");
+        } else {
+            // 添加开根号
+            int sqrtNum = getRandomPerfectSquare();
+            expression.append("√").append(sqrtNum);
+        }
+        
+        return new MathQuestion(expression.toString(), "计算结果");
+    }
+    
+    /**
+     * 生成高中题目：至少有一个sin、cos或tan运算符
+     */
+    private MathQuestion generateHighSchoolQuestion() {
+        StringBuilder expression = new StringBuilder();
+        
+        // 基础部分
+        int num1 = random.nextInt(100) + 1;
+        String op = operators[random.nextInt(operators.length)];
+        
+        // 添加三角函数
+        String trigFunc = trigFunctions[random.nextInt(trigFunctions.length)];
+        int angle = random.nextInt(360); // 0-359度
+        
+        expression.append(num1).append(" ").append(op).append(" ").append(trigFunc).append("(").append(angle).append("°)");
+        
+        return new MathQuestion(expression.toString(), "计算结果");
+    }
+    
+    /**
+     * 为表达式添加括号
+     */
+    private StringBuilder addParentheses(String expression) {
+        String[] parts = expression.split(" ");
+        if (parts.length >= 5) { // 至少有3个数字和2个操作符
+            StringBuilder result = new StringBuilder();
+            result.append("(").append(parts[0]).append(" ").append(parts[1]).append(" ").append(parts[2]).append(")");
+            for (int i = 3; i < parts.length; i++) {
+                result.append(" ").append(parts[i]);
+            }
+            return result;
+        }
+        return new StringBuilder(expression);
+    }
+    
+    /**
+     * 获取随机完全平方数
+     */
+    private int getRandomPerfectSquare() {
+        int[] perfectSquares = {1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400};
+        return perfectSquares[random.nextInt(perfectSquares.length)];
+    }
+}
diff --git a/src/MathTestGenerator.java b/src/MathTestGenerator.java
new file mode 100644
index 0000000..ed274e5
--- /dev/null
+++ b/src/MathTestGenerator.java
@@ -0,0 +1,196 @@
+import java.util.*;
+
+/**
+ * 中小学数学卷子自动生成程序 - 主程序
+ * 实现用户登录、题目生成、类型切换等功能
+ */
+public class MathTestGenerator {
+    private UserManager userManager;
+    private MathQuestionGenerator questionGenerator;
+    private QuestionManager questionManager;
+    private Scanner scanner;
+    private User currentUser;
+    private String currentAccountType;
+    
+    public MathTestGenerator() {
+        this.userManager = new UserManager();
+        this.questionGenerator = new MathQuestionGenerator();
+        this.questionManager = new QuestionManager();
+        this.scanner = new Scanner(System.in);
+        this.currentUser = null;
+        this.currentAccountType = null;
+    }
+    
+    /**
+     * 程序主入口
+     */
+    public void run() {
+        System.out.println("=== 中小学数学卷子自动生成程序 ===");
+        
+        while (true) {
+            if (currentUser == null) {
+                // 未登录状态
+                if (!login()) {
+                    continue; // 登录失败，重新登录
+                }
+            } else {
+                // 已登录状态
+                handleLoggedInUser();
+            }
+        }
+    }
+    
+    /**
+     * 处理用户登录
+     * @return 登录是否成功
+     */
+    private boolean login() {
+        System.out.print("请输入用户名和密码（用空格隔开）：");
+        System.out.flush(); // 强制刷新输出缓冲区
+        
+        String input = scanner.nextLine().trim();
+        
+        if (input.isEmpty()) {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+        
+        String[] credentials = input.split("\\s+");
+        if (credentials.length != 2) {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+        
+        String username = credentials[0];
+        String password = credentials[1];
+        
+        User user = userManager.authenticate(username, password);
+        if (user != null) {
+            currentUser = user;
+            currentAccountType = user.getAccountType();
+            System.out.println("当前选择为" + currentAccountType + "出题");
+            return true;
+        } else {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+    }
+    
+    /**
+     * 处理已登录用户的操作
+     */
+    private void handleLoggedInUser() {
+        System.out.print("准备生成" + currentAccountType + "数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：");
+        System.out.flush();
+        
+        String input = scanner.nextLine().trim();
+        
+        // 检查是否是切换类型命令
+        if (input.startsWith("切换为")) {
+            handleAccountTypeSwitch(input);
+            return;
+        }
+        
+        try {
+            int count = Integer.parseInt(input);
+            
+            if (count == -1) {
+                // 退出当前用户
+                currentUser = null;
+                currentAccountType = null;
+                System.out.println("已退出当前用户");
+                return;
+            }
+            
+            if (count < 10 || count > 30) {
+                System.out.println("题目数量必须在10-30之间，请重新输入");
+                return;
+            }
+            
+            // 生成题目
+            generateAndSaveQuestions(count);
+            
+        } catch (NumberFormatException e) {
+            System.out.println("请输入有效的数字或切换命令");
+        }
+    }
+    
+    /**
+     * 处理账户类型切换
+     * @param input 用户输入
+     */
+    private void handleAccountTypeSwitch(String input) {
+        String newType = input.substring(3); // 去掉"切换为"
+        
+        if (!userManager.isValidAccountType(newType)) {
+            System.out.println("请输入小学、初中和高中三个选项中的一个");
+            return;
+        }
+        
+        currentAccountType = newType;
+        System.out.print("准备生成" + currentAccountType + "数学题目，请输入生成题目数量：");
+        System.out.flush();
+        
+        String countInput = scanner.nextLine().trim();
+        try {
+            int count = Integer.parseInt(countInput);
+            
+            if (count < 10 || count > 30) {
+                System.out.println("题目数量必须在10-30之间");
+                return;
+            }
+            
+            generateAndSaveQuestions(count);
+            
+        } catch (NumberFormatException e) {
+            System.out.println("请输入有效的数字");
+        }
+    }
+    
+    /**
+     * 生成并保存题目
+     * @param count 题目数量
+     */
+    private void generateAndSaveQuestions(int count) {
+        System.out.println("正在生成" + count + "道" + currentAccountType + "数学题目...");
+        
+        // 生成不重复的题目
+        List<MathQuestion> questions = questionManager.generateUniqueQuestions(
+            currentAccountType, count, questionGenerator);
+        
+        if (questions.size() < count) {
+            System.out.println("注意：由于去重要求，实际生成了" + questions.size() + "道题目");
+        }
+        
+        if (questions.isEmpty()) {
+            System.out.println("无法生成新的题目，可能所有题目都已存在");
+            return;
+        }
+        
+        // 保存到文件
+        String fileName = questionManager.saveQuestionsToFile(currentAccountType, questions);
+        if (fileName != null) {
+            System.out.println("题目已保存到文件：" + currentAccountType + "/" + fileName);
+            System.out.println("共生成" + questions.size() + "道题目");
+            
+            // 显示前几道题目作为预览
+            System.out.println("\n题目预览：");
+            for (int i = 0; i < Math.min(3, questions.size()); i++) {
+                System.out.println((i + 1) + ". " + questions.get(i).getExpression());
+            }
+            if (questions.size() > 3) {
+                System.out.println("...");
+            }
+        } else {
+            System.out.println("保存文件失败");
+        }
+    }
+    
+    /**
+     * 程序入口点
+     */
+    public static void main(String[] args) {
+        MathTestGenerator generator = new MathTestGenerator();
+        generator.run();
+    }
+}
diff --git a/src/QuestionManager.java b/src/QuestionManager.java
new file mode 100644
index 0000000..ad3c8f7
--- /dev/null
+++ b/src/QuestionManager.java
@@ -0,0 +1,162 @@
+import java.io.*;
+import java.nio.file.*;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.*;
+
+/**
+ * 题目管理器
+ * 负责题目重复检查和文件保存
+ */
+public class QuestionManager {
+    private Map<String, Set<String>> userQuestions; // 存储每个用户的历史题目
+    
+    public QuestionManager() {
+        this.userQuestions = new HashMap<>();
+        loadExistingQuestions();
+    }
+    
+    /**
+     * 加载已存在的题目文件，用于重复检查
+     */
+    private void loadExistingQuestions() {
+        try {
+            // 为每个用户类型创建目录
+            createDirectoryIfNotExists("小学");
+            createDirectoryIfNotExists("初中");
+            createDirectoryIfNotExists("高中");
+            
+            // 扫描已存在的文件并加载题目
+            scanExistingFiles("小学");
+            scanExistingFiles("初中");
+            scanExistingFiles("高中");
+        } catch (Exception e) {
+            System.err.println("加载历史题目时出错: " + e.getMessage());
+        }
+    }
+    
+    /**
+     * 创建目录
+     */
+    private void createDirectoryIfNotExists(String accountType) throws IOException {
+        Path path = Paths.get(accountType);
+        if (!Files.exists(path)) {
+            Files.createDirectories(path);
+        }
+    }
+    
+    /**
+     * 扫描已存在的文件
+     */
+    private void scanExistingFiles(String accountType) {
+        try {
+            Path accountDir = Paths.get(accountType);
+            if (Files.exists(accountDir)) {
+                Files.walk(accountDir)
+                    .filter(Files::isRegularFile)
+                    .filter(path -> path.toString().endsWith(".txt"))
+                    .forEach(this::loadQuestionsFromFile);
+            }
+        } catch (IOException e) {
+            System.err.println("扫描文件时出错: " + e.getMessage());
+        }
+    }
+    
+    /**
+     * 从文件加载题目
+     */
+    private void loadQuestionsFromFile(Path filePath) {
+        try {
+            String accountType = filePath.getParent().getFileName().toString();
+            Set<String> questions = userQuestions.computeIfAbsent(accountType, k -> new HashSet<>());
+            
+            List<String> lines = Files.readAllLines(filePath);
+            for (String line : lines) {
+                line = line.trim();
+                if (line.matches("\\d+\\..*")) { // 题号格式：1. 题目内容
+                    String question = line.substring(line.indexOf('.') + 1).trim();
+                    questions.add(question);
+                }
+            }
+        } catch (IOException e) {
+            System.err.println("读取文件时出错: " + e.getMessage());
+        }
+    }
+    
+    /**
+     * 检查题目是否重复
+     * @param accountType 账户类型
+     * @param newQuestions 新题目列表
+     * @return 去重后的题目列表
+     */
+    public List<MathQuestion> checkAndRemoveDuplicates(String accountType, List<MathQuestion> newQuestions) {
+        Set<String> existingQuestions = userQuestions.computeIfAbsent(accountType, k -> new HashSet<>());
+        List<MathQuestion> uniqueQuestions = new ArrayList<>();
+        
+        for (MathQuestion question : newQuestions) {
+            if (!existingQuestions.contains(question.getExpression())) {
+                uniqueQuestions.add(question);
+                existingQuestions.add(question.getExpression());
+            }
+        }
+        
+        return uniqueQuestions;
+    }
+    
+    /**
+     * 保存题目到文件
+     * @param accountType 账户类型
+     * @param questions 题目列表
+     * @return 保存的文件名
+     */
+    public String saveQuestionsToFile(String accountType, List<MathQuestion> questions) {
+        try {
+            // 生成文件名：年-月-日-时-分-秒.txt
+            LocalDateTime now = LocalDateTime.now();
+            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd-HH-mm-ss");
+            String fileName = now.format(formatter) + ".txt";
+            
+            // 创建文件路径
+            Path accountDir = Paths.get(accountType);
+            Path filePath = accountDir.resolve(fileName);
+            
+            // 写入文件
+            try (BufferedWriter writer = Files.newBufferedWriter(filePath)) {
+                for (int i = 0; i < questions.size(); i++) {
+                    writer.write((i + 1) + ". " + questions.get(i).getExpression());
+                    writer.newLine();
+                    if (i < questions.size() - 1) {
+                        writer.newLine(); // 题目之间空一行
+                    }
+                }
+            }
+            
+            return fileName;
+        } catch (IOException e) {
+            System.err.println("保存文件时出错: " + e.getMessage());
+            return null;
+        }
+    }
+    
+    /**
+     * 生成指定数量的不重复题目
+     * @param accountType 账户类型
+     * @param requestedCount 请求的题目数量
+     * @param generator 题目生成器
+     * @return 实际生成的题目列表
+     */
+    public List<MathQuestion> generateUniqueQuestions(String accountType, int requestedCount, MathQuestionGenerator generator) {
+        List<MathQuestion> allQuestions = new ArrayList<>();
+        int maxAttempts = requestedCount * 3; // 最多尝试3倍数量
+        int attempts = 0;
+        
+        while (allQuestions.size() < requestedCount && attempts < maxAttempts) {
+            List<MathQuestion> newQuestions = generator.generateQuestions(accountType, requestedCount - allQuestions.size());
+            List<MathQuestion> uniqueQuestions = checkAndRemoveDuplicates(accountType, newQuestions);
+            allQuestions.addAll(uniqueQuestions);
+            attempts++;
+        }
+        
+        return allQuestions;
+    }
+}
diff --git a/src/SimpleMathTestGenerator.java b/src/SimpleMathTestGenerator.java
new file mode 100644
index 0000000..b4c612f
--- /dev/null
+++ b/src/SimpleMathTestGenerator.java
@@ -0,0 +1,200 @@
+import java.util.*;
+import java.io.*;
+
+/**
+ * 简化版中小学数学卷子自动生成程序
+ * 更好的中文支持和用户交互
+ */
+public class SimpleMathTestGenerator {
+    private UserManager userManager;
+    private MathQuestionGenerator questionGenerator;
+    private QuestionManager questionManager;
+    private BufferedReader reader;
+    private User currentUser;
+    private String currentAccountType;
+    
+    public SimpleMathTestGenerator() {
+        this.userManager = new UserManager();
+        this.questionGenerator = new MathQuestionGenerator();
+        this.questionManager = new QuestionManager();
+        this.reader = new BufferedReader(new InputStreamReader(System.in));
+        this.currentUser = null;
+        this.currentAccountType = null;
+    }
+    
+    /**
+     * 程序主入口
+     */
+    public void run() {
+        System.out.println("=== 中小学数学卷子自动生成程序 ===");
+        System.out.println("预设账户：");
+        System.out.println("小学：张三1/张三2/张三3，密码：123");
+        System.out.println("初中：李四1/李四2/李四3，密码：123");
+        System.out.println("高中：王五1/王五2/王五3，密码：123");
+        System.out.println();
+        
+        try {
+            while (true) {
+                if (currentUser == null) {
+                    if (!login()) {
+                        continue;
+                    }
+                } else {
+                    handleLoggedInUser();
+                }
+            }
+        } catch (IOException e) {
+            System.out.println("程序输入输出错误：" + e.getMessage());
+        }
+    }
+    
+    /**
+     * 处理用户登录
+     */
+    private boolean login() throws IOException {
+        System.out.print("请输入用户名和密码（用空格隔开）：");
+        String input = reader.readLine();
+        
+        if (input == null || input.trim().isEmpty()) {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+        
+        input = input.trim();
+        String[] credentials = input.split("\\s+");
+        if (credentials.length != 2) {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+        
+        String username = credentials[0];
+        String password = credentials[1];
+        
+        User user = userManager.authenticate(username, password);
+        if (user != null) {
+            currentUser = user;
+            currentAccountType = user.getAccountType();
+            System.out.println("当前选择为" + currentAccountType + "出题");
+            return true;
+        } else {
+            System.out.println("请输入正确的用户名、密码");
+            return false;
+        }
+    }
+    
+    /**
+     * 处理已登录用户的操作
+     */
+    private void handleLoggedInUser() throws IOException {
+        System.out.print("准备生成" + currentAccountType + "数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：");
+        String input = reader.readLine();
+        
+        if (input == null) {
+            return;
+        }
+        
+        input = input.trim();
+        
+        // 检查是否是切换类型命令
+        if (input.startsWith("切换为")) {
+            handleAccountTypeSwitch(input);
+            return;
+        }
+        
+        try {
+            int count = Integer.parseInt(input);
+            
+            if (count == -1) {
+                currentUser = null;
+                currentAccountType = null;
+                System.out.println("已退出当前用户");
+                return;
+            }
+            
+            if (count < 10 || count > 30) {
+                System.out.println("题目数量必须在10-30之间，请重新输入");
+                return;
+            }
+            
+            generateAndSaveQuestions(count);
+            
+        } catch (NumberFormatException e) {
+            System.out.println("请输入有效的数字或切换命令");
+        }
+    }
+    
+    /**
+     * 处理账户类型切换
+     */
+    private void handleAccountTypeSwitch(String input) throws IOException {
+        String newType = input.substring(3);
+        
+        if (!userManager.isValidAccountType(newType)) {
+            System.out.println("请输入小学、初中和高中三个选项中的一个");
+            return;
+        }
+        
+        currentAccountType = newType;
+        System.out.print("准备生成" + currentAccountType + "数学题目，请输入生成题目数量：");
+        String countInput = reader.readLine();
+        
+        if (countInput == null) {
+            return;
+        }
+        
+        try {
+            int count = Integer.parseInt(countInput.trim());
+            
+            if (count < 10 || count > 30) {
+                System.out.println("题目数量必须在10-30之间");
+                return;
+            }
+            
+            generateAndSaveQuestions(count);
+            
+        } catch (NumberFormatException e) {
+            System.out.println("请输入有效的数字");
+        }
+    }
+    
+    /**
+     * 生成并保存题目
+     */
+    private void generateAndSaveQuestions(int count) {
+        System.out.println("正在生成" + count + "道" + currentAccountType + "数学题目...");
+        
+        List<MathQuestion> questions = questionManager.generateUniqueQuestions(
+            currentAccountType, count, questionGenerator);
+        
+        if (questions.size() < count) {
+            System.out.println("注意：由于去重要求，实际生成了" + questions.size() + "道题目");
+        }
+        
+        if (questions.isEmpty()) {
+            System.out.println("无法生成新的题目，可能所有题目都已存在");
+            return;
+        }
+        
+        String fileName = questionManager.saveQuestionsToFile(currentAccountType, questions);
+        if (fileName != null) {
+            System.out.println("题目已保存到文件：" + currentAccountType + "/" + fileName);
+            System.out.println("共生成" + questions.size() + "道题目");
+            
+            System.out.println("\n题目预览：");
+            for (int i = 0; i < Math.min(3, questions.size()); i++) {
+                System.out.println((i + 1) + ". " + questions.get(i).getExpression());
+            }
+            if (questions.size() > 3) {
+                System.out.println("...");
+            }
+            System.out.println();
+        } else {
+            System.out.println("保存文件失败");
+        }
+    }
+    
+    public static void main(String[] args) {
+        SimpleMathTestGenerator generator = new SimpleMathTestGenerator();
+        generator.run();
+    }
+}
diff --git a/src/User.java b/src/User.java
new file mode 100644
index 0000000..82b8208
--- /dev/null
+++ b/src/User.java
@@ -0,0 +1,35 @@
+/**
+ * 用户账户类
+ * 存储用户信息和账户类型
+ */
+public class User {
+    private String username;
+    private String password;
+    private String accountType; // 小学、初中、高中
+    
+    public User(String username, String password, String accountType) {
+        this.username = username;
+        this.password = password;
+        this.accountType = accountType;
+    }
+    
+    public String getUsername() {
+        return username;
+    }
+    
+    public String getPassword() {
+        return password;
+    }
+    
+    public String getAccountType() {
+        return accountType;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" +
+                "username='" + username + '\'' +
+                ", accountType='" + accountType + '\'' +
+                '}';
+    }
+}
diff --git a/src/UserManager.java b/src/UserManager.java
new file mode 100644
index 0000000..9ed4031
--- /dev/null
+++ b/src/UserManager.java
@@ -0,0 +1,59 @@
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * 用户管理器
+ * 负责用户认证和管理预设账户
+ */
+public class UserManager {
+    private Map<String, User> users;
+    
+    public UserManager() {
+        users = new HashMap<>();
+        initializeUsers();
+    }
+    
+    /**
+     * 初始化预设账户
+     * 根据附表1：小学、初中、高中各3个账户
+     */
+    private void initializeUsers() {
+        // 小学账户
+        users.put("张三1", new User("张三1", "123", "小学"));
+        users.put("张三2", new User("张三2", "123", "小学"));
+        users.put("张三3", new User("张三3", "123", "小学"));
+        
+        // 初中账户
+        users.put("李四1", new User("李四1", "123", "初中"));
+        users.put("李四2", new User("李四2", "123", "初中"));
+        users.put("李四3", new User("李四3", "123", "初中"));
+        
+        // 高中账户
+        users.put("王五1", new User("王五1", "123", "高中"));
+        users.put("王五2", new User("王五2", "123", "高中"));
+        users.put("王五3", new User("王五3", "123", "高中"));
+    }
+    
+    /**
+     * 验证用户登录
+     * @param username 用户名
+     * @param password 密码
+     * @return 验证成功返回User对象，失败返回null
+     */
+    public User authenticate(String username, String password) {
+        User user = users.get(username);
+        if (user != null && user.getPassword().equals(password)) {
+            return user;
+        }
+        return null;
+    }
+    
+    /**
+     * 检查账户类型是否有效
+     * @param accountType 账户类型
+     * @return 是否有效
+     */
+    public boolean isValidAccountType(String accountType) {
+        return "小学".equals(accountType) || "初中".equals(accountType) || "高中".equals(accountType);
+    }
+}