More trees have to be planted to protect the environment and keep the b ______ of nature.

閱讀下面一段文字，找出“碳鏈?zhǔn)椒磻?yīng)”過程的三個(gè)關(guān)鍵性詞語。

科學(xué)家在喀斯特地貌的研究中，發(fā)現(xiàn)了一個(gè)復(fù)雜的碳鏈?zhǔn)椒磻?yīng)。當(dāng)水流從空氣中“大口吮吸”二氧化碳并侵蝕石灰?guī)r時(shí)，持續(xù)不斷的吸碳過程就開始了。接著，在巖石表面自由流淌的酸性水流攜帶著大量碳酸氫根，隨著自然界的水循環(huán)轉(zhuǎn)輾奔向江河湖海。此時(shí)，浮游植物體內(nèi)的“食物加工廠”在急切地“找米下鍋”，它們驚喜地發(fā)現(xiàn)，只要分泌一種叫做“碳酸酐酶”的催化劑，對水中的碳酸氫根“略施魔法”，等待加工的“米”——二氧化碳，就唾手可得。最終，光合作用將大量隨波逐流的碳轉(zhuǎn)化成有機(jī)碳，封存與水生植物體內(nèi)。

Calileo lived in the city of Pisa, _____ there is a leaning tower about 180 feet _____.

A. in which; in which 　 B. where; in leight

C. which; high 　 　　　D. where; leight

Computer science__________(teach)now almost in all universities and institutes.

– Do you think it’s a good idea to make friends with your students?

-- _____, I do. I think it’s a great idea.

　 A. Really　　 B. Obviously　　 C. Actually　　　 D. Generally

______ people have come to realize the importance of learning English. Now they

go to various sorts of schools to take up English courses of one kind or another.

A. Hundred and thousand B. One hundred and thousand of

C. The large number of　 D. Hundreds of thousands of

The English Channel ________ the Great Britain ________ the Continent.

A. cuts; to 　　　　 B. divides; into 　 C. separates; from 　　 D. divides; from

The cause of his death __ his careless driving after too much wine.

A. led to　　　　　 B. caused　　　 C. lay in　　　　 D. resulted in

____ only book knowledge, you will not be able to work well.

A. Had　　 　B. Have　　 C. Having　 　　 D. To have

With so many problems to deal with, they____ another difficult year.

A. are having　 B. are to have　 C. are going to have　 D. have