问题 单项选择题

在对使用五大湖中的两个湖的十处沙滩的8000多人的调查研究中,多伦多大学的生态学家们发现游泳的人中呼吸疾病和胃肠疾病的患病率达69.6%,而没有游泳的人这两类病的患病率是29.5%。
从上述数据能最恰当地得出如下哪个结论

A.人们容易低估在这些湖中游泳的危险。
B.在这两个湖中任意一个湖中游泳患上呼吸道和胃肠疾病的患病率比在其他湖中游泳的患病率高。
C.除了呼吸道、胃肠疾病外的疾病不大可能与在这两个湖中的一个湖中游泳有关。
D.在这些湖中游泳与呼吸道、胃肠疾病之间的联系为这二者之间的因果关系提供了证据。
E.在这些湖中游泳的一大部分人对游泳可能引起的疾病有免疫力。

答案

参考答案:D

解析:游泳的人患率69.6%明显高于没有游泳的患病率29.5%,所以在湖中游泳和患病之间具有因果关系。

单项选择题
单项选择题

Drug use is rising dramatically among the nation’ s youth after a decade of decline. From 1993 to 1994, marijuana use among young people (1) from 12 to 17 jumped 50 percent. One in five high school seniors (2) marijuana daily. Monitoring the Future, which (3) student drug use annually, reports that negative attitudes about drugs have declined for the fourth year in a row. (4) young people see great risk in using drugs. Mood-altering pharmaceutical drugs are (5) new popularity among young people. Ritalin, (6) as a diet pill in the 1970s and now used to (7) hyperactive children, has become a (8) drug on college campuses. A central nervous system (9) , Ritalin can cause strokes, hypertension, and seizures. Rohypnol, produced in Europe as a (10) tranquilizer, lowers inhibitions and suppresses short-term memory, which has led to some women being raped by men they are going out with. (11) taken with alcohol, its effects are greatly (12) . Rock singer Kurt Cobain collapsed from an (13) of Rohypnol and champagne a month before he committed (14) in 1994. In Florida and Texas, Rohypnol has become widely abused among teens, who see the drug as a less expensive (15) for marijuana and LSD. Alcohol and tobacco use is increasing among teenagers, (16) younger adolescents. Each year, more than one million teens become regular smokers, (17) they cannot legally purchase tobacco. By 12th grade, one in three students smokes. In 1995, one in five 14-year-olds reported smoking regularly, a 33 percent jump (18) 1991. Drinking among 14-year-olds climbed 50 percent from 1992 to 1994,and all teens reported substantial increases in (19) drinking. In 1995, one in five 10th graders reported having been drunk in the past 30 days. Two-thirds of high school seniors say they know a (20) with a drinking problem.

3()

A.studies

B.researches

C.surveys

D.examines