摘要:20.A.admitted B.wished C.explained D.realized 2 A huge cloud of dust rose and an overpass disappeared.This was the scene in Zhuzhou.Hunan Province on May 17.Nine people were killed and 16 injured. Things were similar last year in the Sichuan earthquake.Thousands of people were buried in the ruins and lost their lives.What if we could have warned them? People are always racking their brains to find a way of preventing buildings’ collapse.Better materials and technology help.but they are not a solution. Just like humans.a building has its own life cycle from “birth to “death .If we know when a building is going to collapse.we can repair it in advance or get out of it before it falls. Now.scientists at the University of Illinois have developed a material that turns red before it breaks.The invention could be used in things like climbing ropes or bridge supports. The research was led by Nancy Sottos.a professor at the university’s Beckman Institute.and Douglas Davis.a graduate research assistant. The secret behind the color­changing material is a type of molecule .A molecule is a group of atoms held together by chemical bonds.Imagine you and your friends standing in a circle.holding hands.Each person stands for one atom.your hands represent the bonds.and the entire circle represents a molecule.If one person lets go of his or her hands.the molecule changes color. The research team put the molecule into a soft material.When the researchers stretched the material.it turned bright red for a few seconds before it broke into two pieces.When they repeatedly stretched and relaxed the material.without breaking it.it only turned a little red. The major problem is that light can get rid of the red color.When the team shone bright light on the molecule.the broken bond was fixed.and the color disappeared. If the bright light keeps the red color from appearing.the material’s warning system will be useless.Scientists still have a lot of work to do before the color­changing molecules can be used outside the lab.

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What an exciting day it was for Jennifer and Valerie! They 26  friends since Grade Three and had  27 many of their high school experiences. Now they were driving together to their final high school event. Today was 28 day at Laman High School.  29 they were close friends, they were different in many ways. Jennifer was a fairly 30  student while Valerie did just enough to get by and was mainly 31  in a good social life.

"Isn't it 32  that we're all finished?" said Valerie. "I'm really looking forward to having a 33  time this summer."

"  34  be nice," Jennifer replied. "I'm afraid I'm going to have to work most of the summer to help pay for my college expenses. "

Jennifer's parents had only a small 35  and she had made up her mind to have a career in which he could 36  all the things her 37  could not.

Valerie,  38  , came firm a fairly wealthy family. She had little desire to work hard for  39  she had always taken for granted.

"I really don't want to go to college for a while," she 40  . "My uncle 41 a restaurant in the Bahamas and he has 42  me to spend a year there 43  a waitress. That should give me plenty of 44  for the beach. "

"It seems 45  will really be going different ways now," thought Jennifer.

1.A.has been       B. were C. had been            D. would be

2.A.learned       B. obtained  C. remembered      D. shared

3.A.exam        B. sports     C. graduatioD. working

4.A.If         B. Because     C. Although    D. When

5.A.diligent          B. polite   C. active        D. favorite

6.A.specialized        B. relievedC. envied   D. interested

7.A.certain          B. great     C. unfortunate        D. annoying

8.A.nice        B. high         C. bad        D. happy

9.A.Can        B. Shall     C. Must        D. Need

10.A.income      B. problem     C. family       D. difference

11.A .afford         B. give      C. support          D. send

12.A .teachers     B. parents    C. friends      D. relatives

13.A.in fact   B. in a way  C. as a result        D.on the contrary

14.A.what            B. whom      C. that        D. these

15.A.admitted B. complain     C. proposed      D. screamed

16.A.opens    B. runs      C. works            D. makes

17.A.helped  B. assured     C. invited          D. promised

18.A.on        B. do       C. like             D. as

19.A.peace      B. work      C. energy            D. time

20.A.I        B. we       C. she             D. they

 

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