维持鼠标按键按下的状态下，用户可以操控箭头键将所选对象向上、下、左或右每次移动1个像素。
While holding down the mouse button, a user can manipulate the arrow keys to move the selection up, down, left, or right-one pixel at a time.
如果您熟悉使用图形用户界面进行应用程序开发的过程，您就能够想象出它是如何工作的：就如同鼠标上的按键被按下和释放一样。
If you're familiar with developing applications using a graphical user interface, you can imagine how it works: it's similar to mouse buttons that are pressed and released.
比如，我们说某个按键控件是受范的，那是因为它可以被鼠标按下。
For example, a button control is pliant because it can be "pushed" by the mouse cursor.
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