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.