diff --git a/eBook/13.2.md b/eBook/13.2.md
index 7091de6..cbfde26 100644
--- a/eBook/13.2.md
+++ b/eBook/13.2.md
@@ -73,4 +73,4 @@ if err != nil {
 
 - [目录](directory.md)
 - 上一节：[错误处理](13.1.md)
-- 下一节：[从 panic 中恢复 （Recover）](13.3.md)
+- 下一节：[从 panic 中恢复（Recover）](13.3.md)
diff --git a/eBook/13.3.md b/eBook/13.3.md
index 378dd75..cb38ce3 100644
--- a/eBook/13.3.md
+++ b/eBook/13.3.md
@@ -1,4 +1,4 @@
-# 13.3 从 panic 中恢复 （Recover）
+# 13.3 从 panic 中恢复（Recover）
 
 正如名字一样，这个（recover）内建函数被用于从 panic 或 错误场景中恢复：让程序可以从 panicking 重新获得控制权，停止终止过程进而恢复正常执行。
 
diff --git a/eBook/13.4.md b/eBook/13.4.md
index e7eb6c2..4acb751 100644
--- a/eBook/13.4.md
+++ b/eBook/13.4.md
@@ -26,45 +26,45 @@ import (
 
 // A ParseError indicates an error in converting a word into an integer.
 type ParseError struct {
-        Index int      // The index into the space-separated list of words.
-        Word  string   // The word that generated the parse error.
-        Err error // The raw error that precipitated this error, if any.
+    Index int      // The index into the space-separated list of words.
+    Word  string   // The word that generated the parse error.
+    Err error // The raw error that precipitated this error, if any.
 }
 
 // String returns a human-readable error message.
 func (e *ParseError) String() string {
-        return fmt.Sprintf("pkg parse: error parsing %q as int", e.Word)
+    return fmt.Sprintf("pkg parse: error parsing %q as int", e.Word)
 }
 
 // Parse parses the space-separated words in in put as integers.
 func Parse(input string) (numbers []int, err error) {
-        defer func() {
-                if r := recover(); r != nil {
-                        var ok bool
-                        err, ok = r.(error)
-                        if !ok {
-                                err = fmt.Errorf("pkg: %v", r)
-                        }
-                }
-        }()
+    defer func() {
+        if r := recover(); r != nil {
+            var ok bool
+            err, ok = r.(error)
+            if !ok {
+                err = fmt.Errorf("pkg: %v", r)
+            }
+        }
+    }()
 
-        fields := strings.Fields(input)
-        numbers = fields2numbers(fields)
-        return
+    fields := strings.Fields(input)
+    numbers = fields2numbers(fields)
+    return
 }
 
 func fields2numbers(fields []string) (numbers []int) {
-        if len(fields) == 0 {
-                panic("no words to parse")
+    if len(fields) == 0 {
+        panic("no words to parse")
+    }
+    for idx, field := range fields {
+        num, err := strconv.Atoi(field)
+        if err != nil {
+            panic(&ParseError{idx, field, err})
         }
-        for idx, field := range fields {
-                num, err := strconv.Atoi(field)
-                if err != nil {
-                        panic(&ParseError{idx, field, err})
-                }
-                numbers = append(numbers, num)
-        }
-        return
+        numbers = append(numbers, num)
+    }
+    return
 }
 
 ```
@@ -81,23 +81,23 @@ import (
 )
 
 func main() {
-        var examples = []string{
-                "1 2 3 4 5",
-                "100 50 25 12.5 6.25",
-                "2 + 2 = 4",
-                "1st class",
-                "",
-        }
+    var examples = []string{
+            "1 2 3 4 5",
+            "100 50 25 12.5 6.25",
+            "2 + 2 = 4",
+            "1st class",
+            "",
+    }
 
-        for _, ex := range examples {
-                fmt.Printf("Parsing %q:\n  ", ex)
-                nums, err := parse.Parse(ex)
-                if err != nil {
-                        fmt.Println(err) // here String() method from ParseError is used
-                        continue
-                }
-                fmt.Println(nums)
+    for _, ex := range examples {
+        fmt.Printf("Parsing %q:\n  ", ex)
+        nums, err := parse.Parse(ex)
+        if err != nil {
+            fmt.Println(err) // here String() method from ParseError is used
+            continue
         }
+        fmt.Println(nums)
+    }
 }
 
 ```
@@ -122,5 +122,5 @@ Parsing "":
 ## 链接
 
 - [目录](directory.md)
-- 上一节：[从 panic 中恢复 （Recover）](13.3.md)
+- 上一节：[从 panic 中恢复（Recover）](13.3.md)
 - 下一节：[一种用闭包处理错误的模式](13.5.md)
diff --git a/eBook/directory.md b/eBook/directory.md
index fb60936..77c3416 100644
--- a/eBook/directory.md
+++ b/eBook/directory.md
@@ -127,7 +127,7 @@
 - 第13章：[错误处理与测试](13.0.md)
     - 13.1 [错误处理](13.1.md)
     - 13.2 [运行时异常和 panic](13.2.md)
-    - 13.3 [从 panic 中恢复 （Recover）](13.3.md)
+    - 13.3 [从 panic 中恢复（Recover）](13.3.md)
     - 13.4 [自定义包中的错误处理和 panicking](13.4.md)
     - 13.5 [一种用闭包处理错误的模式](13.5.md)
     - 13.6 [启动外部命令和程序](13.6.md)