单击中键
Many mice and some touchpads have a middle mouse button. On a mouse with a scroll wheel, you can usually press directly down on the scroll wheel to middle-click. If you don’t have a middle mouse button, you can press the left and right mouse buttons at the same time to middle-click.
如果触摸板支持多指点按，您可以同时按三个手指来完成中键点击。您要在触摸板的设置中启用鼠标点击。
许多程序用中键作为高级的快捷键。
In applications with scrollbars, left-clicking in the empty space of the bar moves the scroll position directly to that place. Middle-clicking moves up to a single page towards that location.
On the desktop, you can quickly open a new window for an application with middle-click. Simply middle-click on the application’s icon. The applications overview is displayed using the grid button in the dash.
Most web browsers allow you to open links in tabs quickly with the middle mouse button. Just click any link with your middle mouse button, and it will open in a new tab.
在文件管理器中，中键有两种用法：如果您点击一个文件夹，它将在新标签打开，这类似于浏览器的行为，如果您点击的是文件，将会打开它就像双击一样。
Some specialized applications allow you to use the middle mouse button for other functions. Search your application’s help for middle-click or middle mouse button.