Each year, road accidents kill a million people and injure millions more . The economic costs are greatest for developing countries . Earlier this year , the United Nations called for a campaign to improve road safety .

     One way to avoid accidents is better driving . Another is better roads and bridges . Engineers in the Unites States have designed ten new concrete mixtures that they think could make bridges last longer .

     Professor Paul Tikalsky leads the experiments by a team at Pennsylvania State University . He says bridges made of concrete now last about twenty-five to thirty-five years . But he says the new mixtures might extend that to seventy –five or even one-hundred years .

     Concrete is made of stone , sand , water and cement(水泥). The materials in the cement hold the concrete together . Ancient Romans built with concrete . Yet strengthened concrete bridges did not appear until the late 1800s . People keep looking for new ways to improve concrete . Professor Tikalsky says it is one of the most complex of all chemical systems .

     The new mixtures designed by his team contain industrial waste products . He says these make the concrete better able to resist damage from water and salt over time . One of the products is fly ash . This is released into the air as pollution when coal is burned .

     Professor Tikalsky says particles (颗粒)of fly ash are almost exactly the same size and chemical structure as Portland cement . This is the most costly material in concrete . So using fly ash to replace some of it would save money .

     The federal government is paying for part of the research . Engineers anywhere can use the technology . Professor Tikalsky says some of the ideas have already been put to use in China , the Philippines and other countries .

Why did the United Nations launch the campaign ?

  A. Because the United Nations wanted to reduce road accidents and economic costs

  B. Because two million people were killed in the accidents .

  C. Because engineers wanted to design ten new concrete mixtures .

  D. Because the United Nations made bridges of the new mixtures which could last for about 20 to 35

   years .

What does the underlined word “ this ” in the sixth paragraph refer to ?

  A. Fly ash      B. Portland cement      C. Sand       D. Chemical

Which of the following statements is TRUE ?

  A. Ten new concrete bridges have already been built in the United States .

  B. A new concrete bridge could last 50 more years than an ordinary concrete one .

  C. People didn’t know how to build with cement until the late 1800s .

  D. Water and salt won’t do any damage to bridges over time .

What does the passage mainly tell us ?

  A. The causes of road accidents .             B. The advantages of fly ash

  C. The measures of avoiding road accidents    D. Latest information about long-life concrete bridges

Each year, road accidents kill a million people and injure millions more . The economic costs are greatest for developing countries . Earlier this year , the United Nations called for a campaign to improve road safety .
One way to avoid accidents is better driving . Another is better roads and bridges . Engineers in the Unites States have designed ten new concrete mixtures that they think could make bridges last longer .
Professor Paul Tikalsky leads the experiments by a team at Pennsylvania State University . He says bridges made of concrete now last about twenty-five to thirty-five years . But he says the new mixtures might extend that to seventy –five or even one-hundred years .
Concrete is made of stone , sand , water and cement(水泥). The materials in the cement hold the concrete together . Ancient Romans built with concrete . Yet strengthened concrete bridges did not appear until the late 1800s . People keep looking for new ways to improve concrete . Professor Tikalsky says it is one of the most complex of all chemical systems .
The new mixtures designed by his team contain industrial waste products . He says these make the concrete better able to resist damage from water and salt over time . One of the products is fly ash . This is released into the air as pollution when coal is burned .
Professor Tikalsky says particles (颗粒)of fly ash are almost exactly the same size and chemical structure as Portland cement . This is the most costly material in concrete . So using fly ash to replace some of it would save money .
The federal government is paying for part of the research . Engineers anywhere can use the technology . Professor Tikalsky says some of the ideas have already been put to use in China , the Philippines and other countries .
【小题1】Why did the United Nations launch the campaign ?

Each year, road accidents kill a million people and injure millions more . The economic costs are greatest for developing countries . Earlier this year , the United Nations called for a campaign to improve road safety .

One way to avoid accidents is better driving . Another is better roads and bridges . Engineers in the Unites States have designed ten new concrete mixtures that they think could make bridges last longer .

Professor Paul Tikalsky leads the experiments by a team at Pennsylvania State University . He says bridges made of concrete now last about twenty-five to thirty-five years . But he says the new mixtures might extend that to seventy –five or even one-hundred years .

Concrete is made of stone , sand , water and cement(水泥). The materials in the cement hold the concrete together . Ancient Romans built with concrete . Yet strengthened concrete bridges did not appear until the late 1800s . People keep looking for new ways to improve concrete . Professor Tikalsky says it is one of the most complex of all chemical systems .

The new mixtures designed by his team contain industrial waste products . He says these make the concrete better able to resist damage from water and salt over time . One of the products is fly ash . This is released into the air as pollution when coal is burned .

Professor Tikalsky says particles (颗粒)of fly ash are almost exactly the same size and chemical structure as Portland cement . This is the most costly material in concrete . So using fly ash to replace some of it would save money .

The federal government is paying for part of the research . Engineers anywhere can use the technology . Professor Tikalsky says some of the ideas have already been put to use in China , the Philippines and other countries .

1.Why did the United Nations launch the campaign ?

years .

2.What does the underlined word “ this ” in the sixth paragraph refer to ?

3.Which of the following statements is TRUE ?

4.What does the passage mainly tell us ?

Each year, road accidents kill a million people and injure millions more . The economic costs are greatest for developing countries . Earlier this year , the United Nations called for a campaign to improve road safety .
One way to avoid accidents is better driving . Another is better roads and bridges . Engineers in the Unites States have designed ten new concrete mixtures that they think could make bridges last longer .
Professor Paul Tikalsky leads the experiments by a team at Pennsylvania State University . He says bridges made of concrete now last about twenty-five to thirty-five years . But he says the new mixtures might extend that to seventy –five or even one-hundred years .
Concrete is made of stone , sand , water and cement(水泥). The materials in the cement hold the concrete together . Ancient Romans built with concrete . Yet strengthened concrete bridges did not appear until the late 1800s . People keep looking for new ways to improve concrete . Professor Tikalsky says it is one of the most complex of all chemical systems .
The new mixtures designed by his team contain industrial waste products . He says these make the concrete better able to resist damage from water and salt over time . One of the products is fly ash . This is released into the air as pollution when coal is burned .
Professor Tikalsky says particles (颗粒)of fly ash are almost exactly the same size and chemical structure as Portland cement . This is the most costly material in concrete . So using fly ash to replace some of it would save money .
The federal government is paying for part of the research . Engineers anywhere can use the technology . Professor Tikalsky says some of the ideas have already been put to use in China , the Philippines and other countries .

1. 1.

   Why did the United Nations launch the campaign ?

   1. A.
      Because the United Nations wanted to reduce road accidents and economic costs
   2. B.
      Because two million people were killed in the accidents .
   3. C.
      Because engineers wanted to design ten new concrete mixtures .
   4. D.
      Because the United Nations made bridges of the new mixtures which could last for about 20 to 35 years .
2. 2.

   What does the underlined word “ this ” in the sixth paragraph refer to ?

   1. A.
      Fly ash
   2. B.
      Portland cement
   3. C.
      Sand
   4. D.
      Chemical
3. 3.

   Which of the following statements is TRUE ?

   1. A.
      Ten new concrete bridges have already been built in the United States .
   2. B.
      A new concrete bridge could last 50 more years than an ordinary concrete one .
   3. C.
      People didn’t know how to build with cement until the late 1800s .
   4. D.
      Water and salt won’t do any damage to bridges over time .
4. 4.

   What does the passage mainly tell us ?

   1. A.
      The causes of road accidents .
   2. B.
      The advantages of fly ash
   3. C.
      The measures of avoiding road accidents
   4. D.
      Latest information about long-life concrete bridges