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
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. 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 a series of lecture on…
17. officer, official
　officer部队的军官，official政府官员 an army officer
18. work, job
　二者均指工作。work不可数，job可数 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 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 The whole nation was sad at the news.
21. cook, cooker
　cook厨师，cooker厨具 He is a good cook.
22. damage, damages
　damage不可数名词, 损害，损失; damages复数形式, 赔偿金 $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 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 Man will conquer nature.
26. chick, chicken
　二者均可指小鸡，chicken还可以当鸡肉 The chicken is delicious.
27. telegram, telegraph
　当电报解时，telegram指具体的，telegraph指抽象的 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
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 His favorite sport is swimming.
30. price, prize
　price价格，prize奖，奖品，奖金 win the first prize The price is high/low