已知物件型别可以是单一呼叫或单一物件。

Well-known object types can be either single call or singleton.

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请注意，呼叫程序码未指定第一个参数，因为它代表要套用运算子的型别，而且编译器已知道物件的型别。

Note that the first parameter is not specified by calling code because it represents the type on which the operator is being applied, and the compiler already knows the type of your object.

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检查指定物件型别是否登录为已知用户端型别。

Checks whether the specified object type is registered as a well-known client type.

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