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

27. telegram, telegraph

　当电报解时，telegram指具体的，telegraph指抽象的a telegram, by telegraph

26. chick, chicken

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

25. man, a man

　man人类，a man一个男人Man will conquer nature.

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

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.

22. damage, damages

　damage不可数名词, 损害，损失; damages复数形式, 赔偿金 $900 damages

21. cook, cooker

　cook厨师，cooker厨具He is a good cook.

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.

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