21. cook，cooker cook厨师，cooker厨具He is a good cook.

22. damage，damages damage不可数名词，损害，损失；damages复数形式，赔偿金 ＄900 damages

23. police，policeman police警察的总称，后接复数谓语动词，policeman 指某个具体的警察The police are questioning everyone in the house.

24. problem，question problem常和困难联系，前面的动词常为think about，solve，raise，question常和疑问联系，多和ask，answer连用

25. man，a man man人类，a man一个男人Man will conquer nature.

26. chick，chicken二者均可指小鸡，chicken还可以当鸡肉The chicken is delicious.

27. telegram，telegraph当电报解时，telegram指具体的，telegraph指抽象的a telegram，by telegraph

28. trip，journey，travel，voyage travel是最常用的，trip指短期的旅途，journey指稍长的旅途，voyage指海上航行a three-day trip

29. sport，game sport多指户外的游戏或娱乐活动，如打球，游泳，打猎，赛马等；game指决定胜负的游戏，通常有一套规则His favorite sport is swimming.

30. price，prize price价格，prize奖，奖品，奖金win the first prize The price is high/low.

31. a number of，the number of a number of许多，谓语动词用复数。the number of...的数目，谓语动词用单数。The number of students is increasing.

32. in front of，in the front of in front of范围外的前面，in the front of范围内的前面In the front of the room sits a boy.

33. of the day，of a day of the day每一天的，当时的，当代的，of a day暂时的，不长久的a famous scientist of the day

34. three of us，the three of us three of us我们（不止三个）中的三个，the three of us我们三个（就三个人）The three of us—Tom，Jack and I went to the cinema.

35. by bus，on the bus by bus表手段，方式，不用冠词，on the bus表范围They went there by bus.

36. for a moment，for the moment for a moment 片刻，一会儿，for the moment暂时，一时Thinking for a moment，he agreed.

37. next year，the next year next year将来时间状语，the next year过去将来时间状语He said he would go abroad the next year.

38. more than a year，more than one year more than a year一年多，more than one year超过一年（两年或三年等）

39. take advice，take the（one's）advice take advice征求意见，take the advice接受忠告He refused to take the advice and failed again.

40. take air，传播，走漏，take the air到户外去，散步We take the air every day.