解决 windows2012 下无法安装 sql2008R2

1. Press the Windows logo key, type control panel, and then click the Control Panel icon.
   
   Note If you are not using a keyboard, swipe in from the right edge of the screen, tap Search, type control panel in the search box, and then tap the displayed Control Panel icon.
2. Click Programs, and then click Turn Windows features on or off.
3. 选中.net3.5 安装，重启服务器。