32. 误) We went to swim in the river in a very hot day. (正) We went to swim in the river on a very hot day.

(析) 具体某一天要用介词on, 又如：on New Years Day

31. (误) He became a writter at his twenties (正) He became a writter in his twenties

(析)这句话应译为：他在20多岁时就成了作家。在某人的一段生活时间段中要用介词in来表示，而在具体岁数时用at来表示。

30. (误) Dont sleep at daytime (正) Dont sleep in daytime.

(析) in 要用于较长的一段时间之内，如：in the morning / afternoon, 或 in the week / month / year. 或 in spring / supper /autumn / winter等等。

29. 误) We got to the top of the mountain in daybreak. (正) We got to the top of the mountain at day break.

(析) at用于具体时刻之前，如：sunrise, midday, noon, sunset, midnight, night。

28. ---- How much ______ the shoes？　---- Five dollars ______ enough.

　A. is；is　 B. are；is　 C. are；are　 D. is；are

[剖析] 答案为B。shoes作主语时，谓语动词应用复数形式；five dollars是一个整体，应按单数对待。

27. I didn't understand __________，so I raised my hand to ask...

　A. what my teacher says　 B. what does my teacher say　C. what my teacher said　 D. what did my teacher say

[剖析] 答案为C。本题为宾语从句，由于需要用陈述语序可排除B、D；另外，主句时态为一般过去时，则从句也要用对应的过去时态，故还可排除A。

26. Lucy usually cleans the cage every two days. (对画线部分提问)_ _______ Lucy usually clean the cage？

[剖析] 答案为How often does。对every two days提问要用how often。

25. ---- Do you often clean your classroom？---- Yes, our classroom ______ every day.

　A. clean　 B. cleans　 C. is cleaned　 D. Cleaned

[剖析] 答案为C。句中有every day，主语为our classroom，故要用一般现在时的被动语态。

24. Be careful when you come _______ the street，because the traffic is very busy

at the moment.A. across　 B. behind　　 C. between　 D. over

[剖析] 答案为A。本题考察方位介词的用法。“过马路”一般为表面横穿，因此要用across。

23. The number of giant pandas is getting ______ because their living areas are becoming farmlands.

　A. less and less　 B. larger and larger　 C. smaller and smaller　 D. fewer and

fewer

[剖析] 答案为C。句意为“大熊猫的数量越来越少因为他们的生存空间正逐渐变成农场”。本题中四个选项都是“比较级+ and + 比较级”的结构，表示“越来越……”。主语为number，只能和large或small搭配。而结合句意可判断答案为C。