其实很简单，但是中文搜索的内容比较啰嗦，七嘴八舌，，不是官方。
下面是官方的检查办法：
https://msdn.microsoft.com/en-us/library/hh925568(v=vs.110).aspx#net_b
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To find .NET Framework versions by viewing the registry (.NET Framework 1-4)
On theStartmenu, chooseRun.
In theOpenbox, enterregedit.exe.
You must have administrative credentials to run regedit.exe.
In the Registry Editor, open the following subkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP
The installed versions are listed under the NDP subkey. The version number is stored in theVersionentry. For the .NET Framework4 theVersionentry is under the Client or Full subkey (under NDP), or under both subkeys.
To find .NET Framework versions by viewing the registry (.NET Framework 4.5 and later)
On theStartmenu, chooseRun.
In theOpenbox, enterregedit.exe.
You must have administrative credentials to run regedit.exe.
In the Registry Editor, open the following subkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full
Note
If theFullsubkey is not present, then you do not have a the .NET Framework 4.5 or later installed.
Check for a DWORD value namedRelease. The existence of theReleaseDWORD indicates that the .NET Framework 4.5 or newer has been installed on that computer.
The value of theReleaseDWORD indicates which version of the .NET Framework is installed.
Value of the Release DWORD
Version
378389
.NET Framework 4.5
378675
.NET Framework 4.5.1 installed with Windows 8.1 or Windows Server 2012 R2
378758
.NET Framework 4.5.1 installed on Windows 8, Windows 7 SP1, or Windows Vista SP2
379893
.NET Framework 4.5.2
393273
.NET Framework 4.6 RC
任何的限制，都是从自己的内心开始的。
