He is sewing a button on.

他把一个纽扣缝上。

First, a general range shall be sketched out with the mouse, then click the function butt<> class="key">on on the menu, and the program will automatically separate the skull, the hypoderm and the ventricles.

先用鼠标勾画出大致范围，然后击菜单项上的功能按钮，程序将除颅骨、皮下组织和脑室。