无法划分网格

[img]file:///C:/Users/YHZ/AppData/Roaming/Tencent/Users/1243032012/QQ/WinTemp/RichOle/SR7J[B$JCKCZ%7DQ9N58W3REE.jpg[/img]
[img]file:///C:/Users/YHZ/AppData/Roaming/Tencent/Users/1243032012/QQ/WinTemp/RichOle/JTJ@C%60J8LV7%7D~FNS]%25G[83B.jpg[/img]
图中所示面为什么不能mesh呢？求高人详解