We must do something useful to _______ pollution.

A. cut off B. cut up C. cut down D. cut in

C 【解析】 句意：我們必須做一切有用的事情來減少污染。cut down意為“減少”；cut off意為“切除”，cut up意為“切碎”，cut in意為“插嘴，干預”，這里是說要“減少”污染，故選C。

Smoking can ________ lung cancer. You had better give it up.

A. work on B. lead to C. take away D. put out

B 【解析】 試題句意：吸煙會引起肺癌。你最好戒煙。A. work on從事；B. lead to引起，導致；C. take away拿走，帶走；D. put out撲滅，熄滅。吸煙引發(fā)肺癌。故選B。

—There are only a few old city walls left.

—Yeah. Most of them ______ in the 1960s.

A. pulled down B. have pulled down C. had pulled down D. were pulled down

D 【解析】 them指代old city walls，是動作的承受者，所以用被動語態(tài)；根據(jù)時間狀語in the 1960s可知用過去時。

—What are the _______ of bike riding?

— It can help cut down air pollution.

A. advantages B. reasons C. results D. ideas

A 【解析】 句意：-騎自行車的好處是什么？-它能幫助減少空氣污染。advantage 意為“優(yōu)點”； B.原因C.結(jié)果D.主意；想法，“幫助減少空氣污染”應該是騎自行車的優(yōu)勢/好處advantage，故選A。

— Are you going to _______ any of the events?

— Yes. Maybe long jump and high jump.

A. take part in B. join

C. attend D. join in

D 【解析】 句意：-你將要參加任何活動嗎？-是，可能是跳遠和跳高。take part in 指參加會議或群眾性活動等，著重說明句子主語參加該項活動并在活動中發(fā)揮作用，這里參加的是“比賽”，不合適，排除A。join有兩個用法：(1)指加入某個黨派，團體組織等，成為其成員之一，意為：“參軍、入團、入黨”等 。(2)和某人一道做某事，其結(jié)構(gòu)為：join sb. in (doing) sth...

Many overseas Chinese look forward to________more about their roots in the summer camp．

A. learn

B. be learning

C. learning

D. be learned

C 【解析】 look forward to短語中，to是介詞，其后應該用v．-ing形式，因此答案為C。

—Most paper is made________wood．

—Yeah．But most books are made________paper．

A. of；of

B. from；from

C. of；from

D. from；of

D 【解析】 be made from由……制成，從制成品上看不出原材料；be made of由……制成，從制成品上可以看出原材料。

—Are you free now?

—No．I have so many chores________today．

A. do

B. to do

C. doing

D. done

B 【解析】 不定式形式作后置定語。

—________free education，the poor children in my hometown can go back to school．

—So can the children in my hometown．

A. Thanks to

B. Instead of

C. As for

D. Towards

A 【解析】 句意：——多虧了免費教育，我家鄉(xiāng)的貧窮孩子們可以重新去上學了�！�—我故鄉(xiāng)的孩子們也是。“多虧了”應該表示為“thanks to”。

（題文）Grandma________us stories when we were very young．

A. used to tell

B. was used to tell

C. is used to tell

D. was used to telling

A 【解析】 本題題意為“我們很小的時候，奶奶常常給我們講故事”�！斑^去常常做某事”應該表示為“used to do sth．”，因此答案為A。