Letters fall from the top down, and immediately eliminate letters, it will disappear, interface is simple and easy to operate A based on Windows form of application, using multithreaded achieved typing practice function, in mainline Cheng Li with Timer controls timing produced Label controls, each Label controls displayed a random produced of letters, each produced a Label on new opened a thread (auxiliary thread), this thread for control Label controls of down mobile, mainline drive monitored keyboard entered, if keyboard entered text and this Label controls of Text same, Label disappears