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

41. in a word, in words
in a word总之，一句话， in words口头上 In a word, you are right.

42. in place of, in the place of
in place of代替，in the place of在…地方 A new building is built in the place of the old one.

43. in secret, in the secret
in secret秘密地，暗自地，偷偷地，一般用作状语；in the secret知道内情，知道秘密，一般用作表语 My mother was in the secret from the beginning.

44. a girl, one girl
a girl可泛指所有女孩, one girl一个女孩 Can one girl carry such a big box?

45. take a chair, take the chair
take a chair相当于sit down坐下，take the chair开始开会

46. go to sea, by sea, by the sea
go to sea当海员，出航，by sea乘船，由海路， by the sea在海边 go by sea

47. the doctor and teacher, the doctor and the teacher
the doctor and teacher指一个人，既是医生又是老师，the doctor and the teacher两个人，一个医生和一个老师 the doctor and teacher is

48. in office, in the office
in office在职的，in the office在办公室里 He is in office, not out of office.

49. in bed, on the bed
in bed卧在床上，on the bed在床上 The book is on the bed. He is ill in bed.

50. in charge of, in the charge of
in charge of管理，负责照料， in the charge of由……照料 He is in charge of the matter. The matter is in the charge of her.

51. in class, in the class
in class在课上，in the class在班级里 He is the best student in the class.

52. on fire, on the fire
on fire着火,on the fire在火上 Put the food on the fire. The house is on fire.

53. out of question, out of the question
out of question毫无疑问的，out of the question不可能的

54. a second, the second
a second又一，再一，the second第…… He won the second prize.

55. by day, by the day
by day白天，by the day按天计算 The workers are paid by the day.

56. the people, a people
the people指人，a people指民族 The Chinese is a peace-loving people.

57. it, one
it同一物体，one同类不同一 I lost my pen. I have to buy a new one.

58. that, this
that指代上文所提到的，this导出下文所要说的 I was ill. That's why...

59. none, nothing, no one
none强调有多少，nothing, no one强调有没有，nothing指物，no one指人 --- How many.../How much...? --- None.

60. anyone, any one
anyone指人，不能接of，any one指人物均可，可接of any one of you