1. 打開 win8 安裝盤，提取 sources/sxs 文件夾到 d:/sources/sxs (或別的盤也行，舉個例子);
2. 打開 c:/windows/system32 文件夾，找到 cmd.exe，右擊，選擇"Run as administrator";
3. 在命令行執行以下命令：
dism.exe /online /enable-feature /featurename:NetFX3 /Source:d:/sources/sxs (就是第一步提取出來的)
大概一兩分鐘就執行完了，執行結果如下：
Deployment Image Servicing and Management tool
Version: 6.2.8250.0
Image Version: 6.2.8250.0
Enabling feature(s)
[==========================100.0%==========================]
The operation completed successfully.
搞定~~
