动词短语 什么时候不用后面的介词 例如 we can't help cheering还是\cheering up whe

we can't help cheering up when we heard this news
Cheer up!It can't be as bad as all that.振作起来!情况不会那么糟.
She cheered up after we had been to see her.我们去看她后,她感到很高兴.
The news cheered him up.这消息使他高兴起来.
A vase of roses cheered up the room.一瓶玫瑰花使得房间里生机盎然.
要看具体哪个动词短语来定