Update 04.2.md

go langue do not has a structure like for ... in ...

zh/04.2.md

@@ -97,7 +97,7 @@
 	slice:=[]string{"apple","pear","banane"}
 	
 	v := r.Form.Get("fruit")
-	for item in slice {
+	for _, item range slice {
 		if item == v {
 			return true
 		}