After it opens, pressing the appropriate letterkey executes the function.
助记符模式打开以后，按下适当的字母键就可以执行相应的功能。
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Remember that you need to press a letterkey or keys to trigger the rocket motion; depending on your computer's speed, you might experience a slight delay before the rockets appear.
A key that, when pressed in combination with another key, gives the other key an alternative meaning; for example, producing an uppercase character when a letterkey is pressed.