是否可以在新的应用程序域中加载针对不同.NET运行时版本的程序集？

I've an application that is based on .NET 2 runtime. I want to add a little bit of support for .NET 4 but don't want to (in the short term), convert the whole application (which is very large) to target .NET 4.I've an application that is based on .NET 2 run