Things similar continuously happened in Haiti and Chile．Thousands of people were

  Things similar continuously happened in Haiti and Chile．Thousands of people were

buried in the earthquake and lost their fives．What if we could have warned them?People are always trying hard to find a way of preventing building collapsing(坍塌)．Better materials and technology help，but are not a solution．Just like humans，a buildinghas its own life circle from  “birth” to “death”．If we know when a building is going tocollapse，we canrepair it in advance or get out before it falls．

    Now, scientists at the University of Illinoishave developed a material that turns red before it breaks．The invention could be used in thingslike climbing ropes，or bridgesupports．The secretbehind the color-changing material is a type of molecule(分子)．A molecule is a group of atoms held together by chemical bonds(化学键)．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 amolecule．If oneperson 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(拉长) the material：it turned bright red a few secondsbefore 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，light can get rid of the red color．When the team shone a bright light onthe molecule，the brokenbond was fixed，and thecolor disappeared．If brightfight keeps the red color from appearing，the material’s warning system will be useless．Scientists still have a lot of work todo before the color-changing molecule can be used outside the lab．

1. The passage mainly about

A. a way of preventing building from breaking down

B. a series of earthquakes in Haiti and Chile

C. a way of warning before buildings collapse

D. a newly-discovered structure of a molecule

2.According to the passage，we can conclude that

A．there areproblems to solve before putting the new material to use

B．scientistshave found the life circle of buildings from “birth” to “death”

C．brightfight makes the red color visible to human eyes[来源:Z&xx&k.Com]

D．the newmaterial is unlikely to be used in building bridges

3.The color-changing molecule can

A．makebuilding materials much stronger[来源:Zxxk.Com]

B．helpbuilding materials get stretched if necessary

C．preventthe earthquake from killing people

D．remindpeople to leave buildings before they fall

4.The warning system is based on the fact that

A．red colorwon’t show up when it meets bright fight

B．a materialwith a certain type of molecule Can turn red when stretched etched

C．a buildinghas its own life circle of “birth” to “death”

D．the brokenbond will fix itself when a molecule meets bright fight

试题答案

【答案】

1.C

2.A

3.D

4.B

【解析】略