阿里云 window server2012安装NET Framework 3.5方法，要分别执行以下五行：

Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU' -Name UseWUServer -Value 0

Restart-Service -Name wuauserv

Install-WindowsFeature Net-Framework-Core

Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU' -Name UseWUServer -Value 1

Restart-Service -Name wuauserv