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

　　D，C，B，C，A

　　大家都害怕癌癥，這種恐慌正在蔓延開(kāi)來(lái)。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(lái)，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(lái)越像一個(gè)巨大的致癌物。有一種多多少少帶點(diǎn)科學(xué)性的普遍說(shuō)法，認(rèn)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(shuō)，直到把整個(gè)環(huán)境都“清潔干凈”，我們才沒(méi)有危險(xiǎn)。然而，數(shù)據(jù)所說(shuō)明的真正含義根本不是這樣。

　　80%這個(gè)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(jì)出來(lái)的。比如，非洲和遠(yuǎn)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(shí)這種影響主要是由個(gè)人的生活方式?jīng)Q定的。所以數(shù)據(jù)不能說(shuō)明全部情況。如果把所有病例合計(jì)起來(lái)，也許各地總體發(fā)病率都大致相同。