问题 单项选择题

Recently, I flew to Las Vegas to attend a meeting. As we were about to arrive, the pilot announced with apology that there would be a slight (16) before setting down. High desert winds had (17) the airport to close all but one runway. He said that we would be (18) the city for a few minutes waiting to (19) . We were also told to remain in our seats meanwhile with our seat belts fastened (20) there might be a few bumps(颠簸). Well, that few minutes turned into about four-five minutes, including a ride that would make a roller coaster(过山车) (21) by comparison. The movement was so fierce that several passengers felt (22) and had to use airsickness bags. As you might guess, that’ s not a good thing to have happen in a(n) (23) space because it only (24) to increase the discomfort of the situation.
About twenty minutes into the adventure, the entire airplane became very (25) There was now a sense of anxiety and fear that could be (26) noticed. Every passenger simply held on for dear life …except one. A (27) was having a good time! With each bump of the (28) , he would let out a giggle (咯咯地笑)of delight. As I observed this, I (29) that he didn’t know he was supposed to be afraid and worried about his (30) . He neither thought about the past nor about the future. Those are what we gown--ups have learned from (31) . He was (32) the ride because he had not yet been taught to fear it. Having understood this, I took a deep breath and (33) back into my seat, pretending I was (34) on a roller coaster. I smiled for the rest of the flight. I even (35) to giggle once or twice, much to the chagrin(随恼) of the man sitting next to me holding the airsickness bag.

Where can we most probably read this text

A.In a research paper,

B.In a short story.

C.In a travel magazine.

D.In a student’s book.

答案

参考答案:D

解析: 由常识可知,本文是一篇科普文,介绍了一些科学知识,所以D(学生课本)比较合适。而A中的research paper意为“研究论文”;B中的a short story意为“短片故事”;C中的travel magazine意为“旅游杂志”。

阅读理解

阅读理解。

                                                       

     Today we tell you about some new understanding of why cutting the main branch of a plant

or tree can lead to better development.

     The findings are from researchers on two_continents.Professor Prezemyslaw Prusinkiewicz

of the University of Calgary in Canada led the research with scientists from Britain and Sweden.

Their study appears in the Proceedings of the National Academy of Sciences.

     Researchers have known since the 1930s that the actively growing tip of a plant produces

a hormone(荷尔蒙)called auxin(生长素).This hormone flows down the main stem.Scientists

say the auxin has an indirect effect on buds(芽)on the side of the stem to prevent branching.

T     hese buds themselves also produce auxin.The research suggests that to grow,they have

to be able to export the hormone into the main stem.But the flow from the stem tip prevents

them from doing this.The researchers wanted to find out how this blocking happens.

     Professor Prusinkiewicz is on leave in Australia,but he sent us an e-mail suggesting a

simple way to understand the process.Think of a major road crowded with traffic.So many

cars are on the main road that the cars on the side roads cannot enter.

     The stem is like the crowded main road.The new research shows that the buds on the

side cannot export their auxin into the main stem because it is too full.But if that main shoot

is pruned(修剪),other buds below it can start exporting.They are no longer prevented from

growing.

     Ottoline Leyser from the University of York says that after a plant is pruned,all the

inhibited(被抑制的)shoot tips compete with each other to grow.In doing this,the branches

influence each other's growth.Nearby shoot tips are more likely to affect each other than those

that are far apart from each other.

     Professor Leyser says the strongest branches grow best,wherever they may be on the

plant.The study found that the main shoot grows the best of all not because of its position at

the top of the plant,but mostly because it got there first.

1.The underlined part "two continents" in Paragraph 2 refers to"__________".

A.Asia and Africa

B.Africa and Europe

C.North America and Europe

D.Australia and Europe

2.Professor Prusinkiewicz compares the cars on the side roads to __________.

A.plant stems  

B.plant buds

C.the leaves of a plant  

D.the roots of a plant

3.To make the buds on the side of the stem to grow better,the main shoot should __________.

A.be cut off

B.be protected

C.be watered as much as possible

D.be given much auxin

4.According to the passage,which of the following is TRUE?

A.Researchers have recently found out that the growing tip of a plant produces hormones.

B.Auxin has a direct effect on buds to keep branches from growing.

C.Buds on the side of the stem can’t produce hormones.

D.In order to grow,the buds on the side of the stem export the hormones into the main stem.

5.Which of the following may be the best title for this passage?

A.Why shoot tips grow fast?

B.When and how to prune plants?

C.Scientists help cut the mystery behind pruning

D.The great scientist-Prezemyslaw Prusinkiewicz

单项选择题