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. incident, accident
incident指小事件，accident指不幸的事故。如：He was killed in the accident.

3. amount, number
amount后接不可数名词， number后接可数名词，如：a number of students。

4. family, house, home
home 指家，包括住处和家人，house指房子、住宅，family指家庭成员，如：My family is a happy one.

5. sound, voice, noise
sound指自然界各种各样的声音，voice指人的嗓音，noise指噪音，如：I hate the loud noise outside.

6. photo, picture, drawing
photo指用照相机拍摄的照片，picture可指相片、图片、电影片，drawing指画的画，如：Let's go and see a good picture.

7. vocabulary, word
vocabulary指词汇，一个人拥有的单词量；word指具体的单词。如：He has a large vocabulary.

8. population, people
population指人口、人数，people指具体的人，如：China has a large population.

9. weather, climate
weather指一天内具体的天气状况，climate指长期的气候状况，如：The climate here is not good for you.

10. road, street, path, way
road指具体的公路、马路，street指街道，path指小路、小径，way指道路、途径。如：take this road; in the street; show me the way to the museum.

11. course, subject
course指课程（可包括多门科目），subject指科目（具体的学科），如：a summer course。

12. custom, habit
custom指传统风俗、习俗，也可指生活习惯，后接to do；habit指生活习惯，习惯成自然，后接of doing。 如：I've got the habit of drinking a lot.

13. 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.， 如：the reason for being late。

14. exercise, exercises, practice
exercise指运动、锻炼（不可数），exercises指练习（可数），practice指（反复做的）练习。如：Practice makes perfect.

15. class, lesson
作“课”解时，两者可以替换；指课文用lesson，指班级或全体学生用class，如：lesson 6; class 5。

16. speech, talk, lecture
speech指在公共场所所做的经过准备的较正式的演说，talk指日常生活中的一般的谈话、讲话，lecture指学术性的演讲、讲课，如：a series of lecture on…

17. officer, official
officer指部队的军官，official指政府官员，如：an army officer 。

18. work, job
二者均指工作，work不可数，job可数，如：a good job。

19. couple, pair
couple主要指人或动物，pair多指由两部分组成的东西，如：a pair of trousers。

20. country, nation, state, land
country侧重指版图、疆域，nation指人民、国民、民族，state侧重指政府、政体，land指国土、国家。如：The whole nation was sad at the news.

21. cook, cooker
cook指厨师，cooker指厨具，如：He is a good cook.

22. damage, damages
damage是不可数名词，指损害、损失；damages为复数形式，指赔偿金，如：$900 damages。

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

24. 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。

25. man, a man
man指人类，a man指一个男人。如：Man will conquer nature.

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

27. telegram, telegraph
当“电报”解时，telegram指具体的，telegraph指抽象的，如：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，如：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。如：His favorite sport is swimming.

30. price, prize
price指价格，prize指奖、奖品、奖金，如：win the first prize The price is high/low.

31. a number of, the number of
a number of指“许多”，谓语动词用复数。the number of指“…的数目”，谓语动词用单数。如：The number of students is increasing.

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

33. of the day, of a day
of the day指每一天的、当时的、当代的，of a day指暂时的、不长久的，如：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）。如：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。如：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”，如：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，如：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”，如：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”，如：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”，如：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”，如：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指知道内情、知道秘密，一般用作表语。如：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指一个女孩，如：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”，如：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指两个人，一个医生和一个老师。

48. in office, in the office
in office“在职的”，in the office“在办公室里”，如：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”，如：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”，如：He is in charge of the matter. The matter is in the charge of her.