Update README-cn.md

Author: aidlearning

README-cn.md

@@ -21,7 +21,7 @@
 目前，AidLearning已在各大App应用中心上线，下载启动次数超过200万。
 
 ##截图
-<img src="http://www.aidlearning.net/showdoc/server/index.php?s=/api/attachment/visitFile/sign/4a72d62cec051582170e99b3584da67c&showdoc=.jpg#align=left&display=inline&height=480&margin=%5Bobject%20Object%5D&name=image.png&originHeight=960&originWidth=470&size=281243&status=done&style=none&width=235" alt="screen1" >
+<img src="http://www.aidlearning.net/showdoc/Public/Uploads/2020-08-13/5f3534f86bc5d.jpg"  width=960 alt="screen1" >
 
 
 ## 开始使用