86、in the works 正在准备阶段
　　
An advanced course in theoreticalchemistry is the works.
　　
87、 keep to oneself
　　
I’m amazed that you still haven’t gotten to know your neighbors.
　　
88、 kill time 浪费时间
　　
Gosh, what can we do to kill the next 10 hours?
　　
89、 leave…up to somebody
　　
We’ll have to leave the decision up to him.
　　
90、 letter of recommendation 推荐信；letter of reference推荐信