21. on holiday 在度假，在休假中

　　When I was on holiday, I visited my uncle. 我在度假的时候去看望了叔叔。

　　22. travel agency旅行社

　　=travel bureau

　　23. take off

　　1)脱下(衣服等), 解(除)掉

　　He took off his wet shoes.他脱下了湿鞋子。

　　2)(飞机)起飞

　　The plane took off on time. It was a smooth take-off.飞机准时起飞。起飞非常顺利。

　　3)匆匆离开

　　The six men got into the car and took off for the park.这六个人上了车，匆匆离开去公园。

　　24. go wrong v. 走错路, 误入岐途, (机器等)发生故障

　　25. in all adv. 总共

　　26. stay away v.外出

　　27. look up 查询(如宾语为代词，则代词放中间)

　　Look up the word in the dictionary.在字典里查单词。

　　相关词组：look for 寻找;look after照顾，照料; look forward to期待;look into调查; look on旁观;look out注意;look out for注意，留心，提防;look over翻阅，查看，检查;look around环视;look through翻阅，查看。

　　28. run after 追逐，追求

　　If you run after two hares, you will catch neither.同时追两只兔子，你一只也抓不到。

　　29. on the air 广播

　　We will be on the air in five minutes.我们五分钟以后开始广播。

　　This programme comes on the air at the same time every day.这个节目每天在同一时间播出。

　　30. think highly/well/much of对……评价很高, 赞赏, 对……印象好

　　He was highly thought of by the manager.经理对他非常赞赏。

　　I think well of your suggestion.我觉得你的建议很好。

　　think badly/nothing/little/lowly of……认为不好, 好……不在意, 不赞成, 觉得……不怎么样

　　I don’t think much of him as a teacher.我觉得他作为一个老师不怎么样。