题目

根据提示填空。（每空1分，共6分。①～③题必做，④、⑤两题任选一题作答。凡出现加字、漏字、错别字中任何一种情况，该空不得分。） ①学而不思则罔，____________________。（孔子《论语》） ②_________________ ，铜雀春深锁二乔。（杜牧《赤壁》） ③范仲淹《渔家傲·秋思》中，表现作者远离家乡为国戍边却未能建立军功，壮志      难酬的诗句是：                    ，                  。 ④郦道元《三峡》中，写出春冬之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 ? 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 . 2.What does the underlined word “ this ” in the sixth paragraph refer to ? A．Fly ash B．Portland cement C．Sand D．Chemical 3.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 . 4.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