设计电路并在电路七段管上显示数字，（1）显示一个数字（2）显示一串数字（3）七段管上数字循环展示，并一直循环(The circuit is designed to display numbers on the seven section of the circuit, (1) display a number (2), display a string of numbers (3), seven sections of the tube on the digital display cycle, and has been circulating)