1.act up 胡闹，出毛病 (来源：EnglishCN英语问答中心[e问e答])

     The children started to act up as soon as the teacher left the room.

     老师一离开教室，孩子们就闹起来了。

     2.ad lib 即兴而作，随口编

     The comedian ad libbed most of his routine.

     那个喜剧演员大多是即兴表演。

     3.blah-blah-blah 说个不停

     All she does is go 'blah-blah-blah' all night.

     她整夜说个不停。

     4.hit it off 投缘，一见如故

     They hit it off instantly and have been good friends ever since.

     他们一见面就很投缘，从此成了好朋友。

     5.zit 青春痘

     Why is it that every time I have a hot date, I break out with a big zit on my face?

     为什么每次我有重要约会时，脸上都会冒出一个很大的青春痘呢？