1. clothes, cloth, clothing
clothes统指各种衣服，谓语动词永远是复数， cloth指布，为不可数名词 clothing 服装的总称，指一件衣服用a piece of, an article of
2. amount, number
amount后接不可数名词， number后接可数名词 a number of students
3. sound, voice, noise
sound自然界各种各样的声音，voice人的嗓音，noise噪音I hate the loud noise outside.
4. cause, reason
cause 指造成某一事实或现象的直接原因，后接of sth./doing sth，reason用来解释某种现象或结果的理由，后接for sth./doing sth. the reason for being late
5. exercise, exercises, practice
exercise运动，锻炼（不可数），exercises练习（可数），practice（反复做的）练习 Practice makes perfect.
6. officer, official
officer部队的军官，official政府官员 an army officer
7. work, job
二者均指工作。work不可数，job可数 a good job
8. cook, cooker
cook厨师，cooker厨具 He is a good cook.
9. problem, question
problem常和困难连系，前面的动词常为think about, solve, raise，question常和疑问连系，多和ask, answer连用
10. 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.
11. chick, chicken
二者均可指小鸡，chicken还可以当鸡肉 The chicken is delicious.
12. 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
13. 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.
14. 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.
15. 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.
16. 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.
17. in a word, in words
in a word总之，一句话， in words口头上 In a word, you are right.
18. 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.
19. 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
20. 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
21. 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.
22. 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.
23. out of question, out of the question
out of question毫无疑问的，out of the question不可能的
24. a second, the second
a second又一，再一，the second第…… He won the second prize.
25. by day, by the day
by day白天，by the day按天计算 The workers are paid by the day.
26. it, one
it同一物体，one同类不同一 I lost my pen. I have to buy a new one.
27. 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.
28. other, another
other后接名词复数，another后接名词单数 other students, another student
29. not a little, not a bit
not a little非常，not a bit一点也不 I’m not a bit tired. 我一点儿也不累。
30. many, much, a lot of
many和可数名词连用，much和不可数名词连用，a lot of可数，不可数均可，但不用于否定句 I haven’t many books.
31. no, not
no=not a/any no friend=not a/any friend no water=not any water
32. no more than, not more than
no more than相当于only，仅仅，只有，not more than 至多，不超过
33. tall, high
tall常指人或动物，high常指物体 He is tall.
34. fast, quickly
fast侧重于指人或物体具有运动速度快的特点，quickly侧重指某事完成或发生的快 run fast, answer the question quickly
35. high, highly
high具体的高，highly抽象的高，高度的 think highly of
36. sleeping, asleep, sleepy
sleeping正在睡觉，asleep睡着，熟睡，只能做表语，sleepy困的，有睡意的 a sleeping baby The baby is asleep. I’m sleepy.
37. respectful, respectable
respectful尊敬，有礼貌，respectable可敬的，值得尊敬的 be respectful to the aged
38. pleasant, pleased, pleasing
pleasant常用作定语，pleased, pleasing常用作表语，pleased主语常为人，pleasing主语常为物 a pleasant trip The trip is pleasing.
39. close, closely
close接近，靠近，closely紧紧地，紧密地 closely connected, stand close
40. ill, sick
ill做表语，sick定，表均可 a sick boy
41. good, well
good形容词，well副词，但指身体状况是形容词 He is well again.
42. hard, hardly
hard努力，hardly几乎不 work hard I can hardly believe it.
43. late, lately
late迟，晚，lately最近，近来 I haven’t seen him lately.
44. living, alive, live, lively
living, alive, live均为活着的，living定表均可，alive定表均可，定语后置，live只能做定语，lively意为活波的 all the living people=all the people alive
45. excited, exciting
excited使人兴奋的，exciting令人兴奋的 I’m excited. The news is exciting.
46. deep, deeply
deep具体的深，deeply抽象的深，深深地 deeply moved, dig deep
47. before long, long before
before long不久以后，long before很久以前 not long before = before long
48. instead, instead of
instead是副词，放在句首或句末，instead of是介词短语，放在句中He didn’t see a film. Instead he watched TV. He watched TV instead of seeing a film.
49. too much, much too
too much 后接不可数名词，much too后接形容词 much too heavy
50. raise, rise
raise及物动词，rise不及物动词 The sun rises in the east.