What are the key differences between .net 4 and .net 3.5

What are the key differences between 开发者_JAVA百科.net 4 and .net 3.5?

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Read this huge list

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Take a look at this :

http://saimaterial.wordpress.com/2009/02/18/key-features-of-microsoft-visual-studio-2010-and-net-40/

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Named arguments and optional parameters is a nice one.