The research is so designed that once nothing can be done to change it. A. begins B. having begun C. beginning D. begun 题目和参考答案——青夏教育精英家教网—

题目内容

The research is so designed that once　　 nothing can be done to change it.

A. begins　　 B. having begun C. beginning D. begun

答案：D
解析：

本题考查非谓语动词的用法。题意为“这项研究计划的如此周密，所以一旦开始做起来，就什么也不能改变它。”句中的once是连词，后可接从句或分词。因为begin与research是被动关系，因此要用过去分词，相当于once it is begun的省略形式。故答案为D。

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(1)

According to the text,there exists a lot of ________ in sweet potatoes．
[　　]
A．	fiber,beta carotene,other earotenoids,vitamin E and C
B．	beta carotene,other carotenoids,fiber,vitamin A and E
C．	vitamin A,beta carotene,fiber,vitamin E and C
D．	beta carotent,other carotenoids,vitamin A and E

(2)

This text as a whole suggests that eating sweet potatoes can help ________
[　　]
A．	cut your risk of stroke and heart disease
B．	protect against breast,lung and stomach cancers
C．	protect against ailments ranging from cataracts to cancer
D．	you stay healthy and reduce your risk of life shortening diseases

(3)

“This vitamin pill in an orange jacket”in the passage refers to ________
[　　]
A．	sweet potato
B．	vitamin C pill
C．	vitamin E pill
D．	beta carotene

(4)

The best title of this passage might be ________
[　　]
A．	The Vitamin Superstar
B．	On Sweet Potatoes
C．	Beta Carotene and Vitamins
D．	Diet and Disease

阅读理解：　　

阅读下面短文，从所给四个选项中，选出最佳答案。

　Can trees talk? Yes——but not in words． Scientists have reason to believe that trees do communicate (互通信息) with each other． Not long ago, resear- chers learned some surprising things． First a willow tree(柳树)attacked in the woods by caterpillars(毛毛虫)changed the chemistry of its leaves and made them taste so terrible that the caterpillars got tired of the leaves and stopped eating them． Then even more astonishing, the tree sent out a special vapour — a signal causing its neighbours to change the chemistry of their own leaves and make them less tasty．

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[　　]

A． changing its leaves’chemistry

B． changing its leaves’colour

C． talking to caterpillars

D． sending a special vapour

2． From the passage we know that catrpillars________．

[　　]

A． like willow trees

B． enjoy eating fallen leaves

C． feed on willow tree leaves

D． could communicate with willow trees

3． Caterpillars will stop eating willow tree leaves which________．

[　　]

A． have a chemical change and become tasteless

B． have a pleasant taste

C． are being attacked

D． are communicating

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[　　]

A． They talk in words．

B． They send out a special vapour．

C． They wave their leaves．

D． They make special sounds．

5． According to the passage, bees communicate with each other by______．

[　　]

A． talking

B． making unusual sounds

C． singing songs

D． fly in certain patterns

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