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
