延续性动词例句：
Sam was hiding behind the door when his mother came in.
句意：当他妈妈进来的时候，山姆正藏在门后。
hide延续性动词，表示动作正在进行，用进行时态，根据came可知用过去进行时，故填was hiding
hide做动词的用法：
He hid the letter in a drawer.他把信藏在抽屉里。
这句话中hid是hide的过去式，意思是藏、隐藏、隐蔽。
He hid behind a false identity.他隐姓埋名。
No amount of make-up could hide her age.再多的化妆品也遮掩不住她的年龄
I have never tried to hide the truth about my past.我从未设法隐瞒我的过去。
