21. back up
　　1) 累积
　　The subway is running behind schedule. and traffic is backed up for blocks. I don’t know if we’ll make the 6:30 show.
　　2) 支持
　　I’ll back it up.
　　22. be bound for 到……地方
　　The bus is bound for New England.
　　23. be (feel) myself 找到自我
　　I’m feeling myself again.
　　24. be burned up 生气
　　She was really burned up at the news.
　　25. be hard up for
　　I’m hard up for clothes, but I have a lot of books.
　　26. be head and shoulders above 好许多
　　In calculus. Joe is head and shoulders above his classmates.
　　27. be in the dark 蒙在鼓里
　　A: Do you have any idea what his notice is about?
　　B: I’m as in the dark as you are.
　　28. be stuck 卡住了
　　I can’t get this window open. It’s stuck.
　　29. bite off more than one can chew. 贪多嚼不烂
　　A: I hear you’re taking an advanced physics course this semester.
　　B: I think I’ve bitten off more than I can chew.
　　30. break new ground 有了新的突破
　　His architectural design broke new ground in the field.
　　31. benefit concert 慈善音乐会
　　We need to let everyone know about the benefit concert, but we don’t have much money for advertising.
　　32. busy signal 占线
　　I’ve been calling David for the past half hour, but I keep getting a busy signal.
　　33.between you and me 你我之间，保密
　　34，call for
　　A.打电话找
　　Tom just called for you.
　　B.预报
　　The forecast calls for heavy rain again tonight. Aren’t you glad we’ll be getting away from this for a week?
　　C.问
　　It’s probably in the new part of town. We’ll have to call for directions.
　　35. call it a day 就此结束
　　A: I’m really glad our club decides to raise money for the children’s hospital and most of the people we’ve phoned seemed happy to contribute.
　　B: Yeah. I agree. Now we’ve gone through all the numbers on our list now, so I guess we can call it a day.
　　36.cash the check 兑现支票
　　Have your sister cashed her paycheck?
　　37.clear off 收拾，整理
　　It’s about time we clear off the desk.
　　38.come down (雨，雪)下起来
　　The heavy rain is coming down. now.
　　39. come in first in the race 比赛第一名
　　Not only did Jill come in first in the race but she also had her best running time of the season.
　　40.come what may 不管怎样
　　We’ll pick you up tomorrow at eight. come what may.