悬停在源输入字段上，单击显示的拖动手柄，但不要按住鼠标按键。

Hover over the source input field, single-click the drag handle that appears but do not hold down the mouse button.

youdao

这时电话，这时话筒，这些是按键，鼠标， 这是键盘，这里有CD，这是订书机，磁带，显示器，CPU。

This is the telephone, this is the receiver. These are the buttons. The mouse. This is the keyboard. Here we have CD's. This is the stapler, tape, monitor, CPU.

youdao