Thread.sleep :Sleep is found on the Thread class. It is a static method that receives one parameter. You must either include System.Threading or use the fully qualified name for the method invocation, which is System.ThreadingThread.Sleep(Parameter);Thread.Sleep(n) means block the current thread for at least the number of timeslices (or thread quantums) that can occur within n milliseconds. Thread.Sleep(n) means block the current thread for at least the number of timeslices (or thread quantums) that can occur within n millisecond.console.clear() :Clears the console buffer and corresponding console window of display information.Console.Clear() to wipe out everything on the screen. I wonder if I can use Console.Readline(valueOne), then output only the answer without the question. If I only asked one question, the Console.ClearStreamwriter :StreamWriter(String) Initializes a new instance of the StreamWriter class for the specified file by using the default encoding and buffer size.+9