diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md
index 26d821bd..012e4066 100644
--- a/problems/0704.二分查找.md
+++ b/problems/0704.二分查找.md
@@ -515,7 +515,8 @@ impl Solution {
 ```
 
 **C:**
-```c(版本一)
+```
+//C (版本一) 左闭右闭区间 [left, right]
 int search(int* nums, int numsSize, int target){
     int left = 0;
     int right = numsSize-1;
@@ -542,13 +543,13 @@ int search(int* nums, int numsSize, int target){
 }
 ```
 ```
-C (版本二)
+C (版本二) 左闭右开区间 [left, right)
 int search(int* nums, int numsSize, int target){
     int length = numsSize;
     int left = 0;
-    int right = length;//定义target在左闭右开的区间里，即：[left, right)
+    int right = length;	//定义target在左闭右开的区间里，即：[left, right)
     int middle = 0;
-    while(left < right){// left == right时，区间[left, right)属于空集，所以用 < 避免该情况
+    while(left < right){  // left == right时，区间[left, right)属于空集，所以用 < 避免该情况
         int middle = left + (right - left) / 2;
         if(nums[middle] < target){
             //target位于(middle , right) 中为保证集合区间的左闭右开性，可等价为[middle + 1,right)
@@ -556,7 +557,7 @@ int search(int* nums, int numsSize, int target){
         }else if(nums[middle] > target){
             //target位于[left, middle)中
             right = middle ;
-        }else{// nums[middle] == target ，找到目标值target
+        }else{	// nums[middle] == target ，找到目标值target
             return middle;
         }
     }