在提示符后从键盘上输入I（或i）进入到频率变化率输入，输入一个数字，按下回车后，喇叭发出声音，声音停止后自动返回到上一步，继续进行操作，或在提示符后从键盘上输入Q（或q）退出这个程序。-at the prompt from the keyboard input I (i) to enter the frequency rate of change, enter a number, Press Enter, the sound from the loudspeaker, the voice stopped automatically after the return to the previous step, continue to operate, at the prompt or keyboard input from the Q (or q) to withdraw from the process.