An application contains code that measures reaction times. The code counts on a thread separate from the user interface. The application includes the following code. (Line numbers are included for reference only.) You need to ensure that the application cancels counting when the user presses the Enter key. Which code segment should you insert at line 14?
正解:A
Explanation/Reference: Explanation: CancellationTokenSource.Dispose() releases all resources used by the current instance of the CancellationTokenSource class. Reference: https://docs.microsoft.com/en-us/previous-versions/windows/silverlight/dotnet-windows-silverlight/ dd321629(v=vs.95)