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则指服装的总称。指一件衣服用a piece of,an article of
2. incident, accident
incident表示某事件的变数、插曲；accident指不幸的事故，但是happy accident表示意外收获。eg：He was killed in the accident.
3. amount, number
amount后接不可数名词，number后接可数名词。eg：a number of students
4. family, house, home
home指家，包括住处和家人；house房子，住宅；family家庭成员。eg：My family is a happy one.
5. 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.
6. photo, picture, drawing
photo用照相机拍摄的照片；picture可指相片，图片，电影片；drawing指画的画
eg：Let's go and see a good picture.
7. vocabulary, word
vocabulary词汇，一个人拥有的单词量；word具体的单词。eg：He has a large vocabulary.
8. population, people
population人口，人数；people具体的人。eg：China has a large population.
9. weather, climate
weather一天内具体的天气状况；climate长期的气候状况。eg：The climate here is not good for you.
10. road, street, path, way
road具体的公路，马路，street街道，path小路，小径，way道路，途径
eg：take this road; in the street, show me the way to the museum
11. course, subject
course课程（可包括多门科目），subject科目（具体的学科）a summer course
12. custom, habit
custom传统风俗，习俗，也可指生活习惯，后接to do；habit生活习惯，习惯成自然，后接o
f doing. eg：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. the reason for being late
14. exercise, exercises, practice
exercise运动，锻炼（不可数），exercises练习（可数），practice（反复做的）练习 
eg：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。eg：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日常生活中的一般的谈话，讲话；lecture学术性的演讲，讲课。eg：a series of lecture 
17. officer, official
officer部队的军官，official政府官员。eg：an army officer
18. work, job
二者均指工作。work不可数，job可数。eg：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。eg：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国土，国家。eg：The whole nation was sad at the news.
21. cook, cooker
cook厨师，cooker厨具。eg：He is a good cook.
clothes和clothing22. damage, damages
damage不可数名词，损害，损失；damages复数形式，赔偿金。eg：$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。eg：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人类，a man一个男人。eg：Man will conquer nature.
26. chick, chicken
二者均可指小鸡，chicken还可以当鸡肉。eg：The chicken is delicious.
27. telegram, telegraph
当电报解时，telegram指具体的，telegraph指抽象的。eg：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。eg：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。eg：His favorite sport is swimming.
30. price, prize
price价格；prize奖，奖品，奖金。eg：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。eg：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。eg：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。eg：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）。eg：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。eg：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。eg：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 
eg：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。eg：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。eg：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。eg： 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。eg：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
eg：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。eg：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。eg：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 
48. in office, in the office
in office在职的，in the office在办公室里。eg：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。 eg：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。 eg：He is in charge of the matter. The matter is in the charge of her.