The 80-percent calculation is based on the unthinkable differences in the incidence of cancer in various societies around the world — for example, the high proportion of liver cancer in Africa and the Far East, stomach cancer in Japan, breast cancer in Western Europe and North America, and the relatively low figures for breast cancer in Japan and parts of Africa and for liver cancer in America. These data indicate there may be special and specific environmental influences, largely based on personal life-style, that determine the incidence of various forms of cancer in different communities — but that is all the data suggest. The overall incidence of cancer, counting up all the cases, is probable roughly the same everywhere.

　　1.Which of the following is closest to meaning to the phrase “leveling off”?

　　A)Became very popular

　　B)Reached its lowest level in popularity

　　C)Stopped being popular

　　D)Stopped increasing its popularity

　　2.According to the passage, the incidence of cancer is generally believed _____.

　　A)to be based on inactive life style

　　B)to be due to anxiety

　　C)to result from environmental influences

　　D)to be caused by heavy smoking

　　3.It can be inferred from the passage that the writer’s opinion about the relationship between cancer and environment is_____.

　　A)positive

　　B)negative

　　C)neutral

　　D)approving

　　4.According to the passage, the writer seems to feel that_____.

　　A)cancer risk is on the rise

　　B)the whole earth resembles a huge carcinogen

　　C)the risk of catching cancer is not so great as most people conceive

　　D)cancer can be cured sooner or later

　　5.Which of the following would be the best TITLE for the passage?

　　A)Cancer and Environment

　　B)The Fear Caused by Cancers

　　C)Data on Cancer Incidence

　　D)Cancer and its Investigation

　　答案：D，C，B，C，A

　　大家都害怕癌癥，這種恐慌正在蔓延開來。倒不是懼怕癌癥本身，癌癥也并非流行病。除了主要由于抽煙引起的肺癌之外，癌癥的發(fā)病率不但穩(wěn)定下來，而且有些還正在減少。但人們卻都談“癌”色變，陷入一種惶恐不安之中。地球本身看上去就越來越像一個巨大的致癌物。有一種多多少少帶點科學(xué)性的普遍說法，認為80%到90%的癌癥都是由于環(huán)境中的物質(zhì)引起的。也就是說，直到把整個環(huán)境都“清潔干凈”，我們才沒有危險。然而，數(shù)據(jù)所說明的真正含義根本不是這樣。

　　80%這個數(shù)據(jù)是基于全球不同地區(qū)癌癥發(fā)病率的差異統(tǒng)計出來的。比如，非洲和遠東地區(qū)肝癌比例高，日本胃癌比例高，西歐和北美乳腺癌比例高，但是日本和非洲部分地區(qū)乳腺癌病例較少，美洲肝癌病例也較少。這些差異使人難于置信。這些數(shù)據(jù)表明，不同地區(qū)癌癥的發(fā)病率可能受到環(huán)境中某些具體和特殊的影響，其實這種影響主要是由個人的生活方式?jīng)Q定的。所以數(shù)據(jù)不能說明全部情況。如果把所有病例合計起來，也許各地總體發(fā)病率都大致相同。

　　英語四級閱讀理解基礎(chǔ)練習二：

　　Until the 1980s, the American homeless population comprised mainly older males. Today, homelessness strikes much younger part of society. In fact, a 25-city survey by the U. S. Conference of Mayors in 1987 found that families with children make up the fastest growing part of the homeless population. Many homeless children gather in inner cities; this transient(變化無常的) and frequently frightened student population creates additional problems — both legal and educational — for already overburdened urban school administrators and teachers.

　　Estimates of the number of homeless Americans range from 350,000 to three million. Likewise, estimates of the number of homeless school children vary radically. A U.S. Department of Education report, based on state estimates, states that there are 220,000 homeless school-age children, about a third of whom do not attend school on a regular basis, But the National Coalition for the Homeless estimates that there are at least two times as many homeless children, and that less than half of them attend school regularly.　　　　One part of the homeless population that is particularly difficult to count consists of the “throwaway” youths who have been cast of their homes. The Elementary School Center in New York City estimates that there are 1.5 million of them, many of whom are not counted as children because they do not stay in family shelters and tend to live by themselves on the streets.　　　　Federal law, the Stewart B. McKinney Homeless Assistance Act of 1987, includes a section that addresses the educational needs of homeless children. The educational provisions of the McKinney Act are based on the belief that all homeless children have the right to a free, appropriate education.

　　1. It is implied in the first paragraph that ____.

　　A) the writer himself is homeless, even in his eighties

　　B) many older homeless residents are going on strike in 25 cities

　　C) there is a serious shortage of academic facilities

　　D) homeless children are denied the opportunity of receiving free education

　　2. The National Coalition for the homeless believes that the number of homeless children is _____.

　　A) 350,000

　　B) 1,500,000

　　C) 440,000

　　D) 110,000

　　3. One part of the homeless population is difficult to estimate. The reason might well be ____.

　　A) the homeless children are too young to be counted as children

　　B) the homeless population is growing rapidly

　　C) the homeless children usually stay outside school

　　D) some homeless children are deserted by their families

　　4. The McKinney Act is mentioned in this passage in order to show that ___.

　　A) the educational problems of homeless children are being recognized

　　B) the estimates on homeless children are hard to determine

　　C) the address of grade-school children should be located

　　D) all homeless people are entitled to free education

　　5. The passage mainly deals with ____.

　　A) the legal problems of the homeless children

　　B) the educational problems of homeless children

　　C) the social status of older males

　　D) estimates on the homeless population

　　答案：C C D A B

　　直到20世紀80年代，美國無家可歸的人口主要包括的還是年齡較大的男性。現(xiàn)在，社會上年齡較小的一些人也面臨無家可歸的威脅。的確，美國會議在1987年對25個城市進行了一項調(diào)查，結(jié)果表明，在無家可歸的人口中，兒童的增長比例是最快的。許多無家可歸的兒童都聚集在城市的中心地帶。其中學(xué)齡兒童四處流浪，飽受驚嚇。這給已經(jīng)負擔考試大過重的城市教學(xué)和教學(xué)管理帶來了許多額的外的麻煩，其中既涉及法律問題又涉及教育問題。

　　美國無家可歸的人口數(shù)量估計在35萬到300萬人之間。同樣，無家可歸的學(xué)齡兒童人數(shù)也無法做出準確的估計。一份根據(jù)各州估計數(shù)字而得出的美國教法的育部的報告指出，有22萬無家可歸的學(xué)齡兒童，其中約有三分之一沒有按規(guī)定上學(xué)。然而國家關(guān)于無家可歸人員的聯(lián)盟會卻估計，這樣的兒童人數(shù)至少還應(yīng)該多一倍，其中半數(shù)以上沒有正常入學(xué)。考試大

　　有一部分無家可歸的人口尤其難以統(tǒng)計，就是那些遭家庭遺棄的“浪蕩”少年。據(jù)紐約小學(xué)中心估計，這樣的人口有150萬左右。其中還有許多小孩沒有估計進去，因為這些小孩不呆在安全的家中，卻往往獨自在街頭流浪。

　　聯(lián)邦法律(1987年斯圖爾德•B•麥肯尼無家可歸人員救助法案)有一部分專門指出了無家可歸兒童的教育需要。法案中有關(guān)于教育的條款所依據(jù)的觀點是所有無家可歸的兒童都有權(quán)接受正規(guī)的義務(wù)教育