据报道，近日山西临汾有摄影师蹲守三天，拍到了2只火凤凰为了求偶上演风骚走位的画面。
When we define our interfaces in C# 4.0, we are allowed to mark each of the generic parameters as in or out. If we try to set a generic parameter as out and that\'d lead to a problem, the compiler rai
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