diff --git a/chapter4/4.2SparkGraphX计算生成最短路径.md b/chapter4/4.2SparkGraphX计算生成最短路径.md
index ff8bc8b..d462f2c 100644
--- a/chapter4/4.2SparkGraphX计算生成最短路径.md
+++ b/chapter4/4.2SparkGraphX计算生成最短路径.md
@@ -77,7 +77,7 @@
 ```
 //起始顶点id
 val srcVertexId = 1L
-// 调用`pregel`方法之前，首先初始化所有点的值。
+// 调用pregel方法之前，首先初始化所有点的值
 val initialGraph = graph.mapVertices { case (id, (name)) => if (id == srcVertexId) (new ArrayBuffer[Long](),0.0) else (new ArrayBuffer[Long](),Double.PositiveInfinity) }
 
 initialGraph.vertices.foreach(println)  // 后面操作中删除