删除以前版本的.NET框架是否安全？ [重复]

I've just installed the 3.5 .NET Framework and while doing some cleaning I've notice that I have a lot of older versions installed (1.1, 1.1 Hotfix(xxx), 2.0, 2.0 service pack etc...). I wonder if I can safely dispose of all of them or these are needed in case I run a lower version .net application.I've just installed the 3.5 .NET Framework and