is defined in multiple assemblies in the global alias

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.CallerLineNumberAttribute' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.CallerFilePathAttribute' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.CallerMemberNameAttribute' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.AsyncTaskMethodBuilder' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.AsyncTaskMethodBuilder' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.AsyncVoidMethodBuilder' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.IAsyncStateMachine' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.INotifyCompletion' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.ICriticalNotifyCompletion' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Runtime.CompilerServices.AsyncStateMachineAttribute' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Threading.Tasks.Task' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误:

　　警告: CS1685: The predefined type 'System.Threading.Tasks.Task' is defined in multiple assemblies in the global alias; using definition from 'c:WindowsMicrosoft.NETFramework64v4.0.30319mscorlib.dll'

　　源错误: