问题
I have installed Visual Studio 2010 Professional, and despite my tremendous urge to work on it since it is pleasing to the eye, it seems not to support .NET framework 3.5/3.0.
Therefore, I have switched to Visual Studio 2008 rather relunctantly.
How do I add .NET framework 3.0/3.5 to the top right combo box within the make new project?
(Note: In the top right combo box within the make new project, I have only .NET framework 4.0 available.)
回答1:
It should just work absolutely fine - but it depends on the project type. Are you trying to create a Silverlight 4 project or something else that relies on .NET 4?
Try just creating a console application - it should definitely offer .NET 3.5.
I assume you have .NET 3.5 installed?
回答2:
Make sure the 3.5 framework is still installed and hasn't been removed while installing VS2010 with the .NET4 framework. You can donwload the 3.5 framework here
回答3:
I've been having the same issue with VS 2010 not having the earlier .NET frameworks available as a dropdownlist inspite of having all the frameworks installed in the machine. After lots of research I found this link to be just right solution for this problem. It turns out that having .NET 3.5, 2.0 or 3.0 is not alone enough, you also have to install .NET 3.5 SP1 for the earlier ones to be available in VS2010. Hope this helps.
来源：https://stackoverflow.com/questions/2927372/visual-studio-2010-net-framework-3-5-unavailable