问题 选择题

两栖动物是

A.幼体和成体都能生活在水中或陆上的生物

B.既能生活水中,又能生活在陆上的动物

C.幼体在水中,成体只能生活在陆上,用肺兼用皮肤辅助呼吸的动物

D.幼体在水中,用鳃呼吸,成体营水陆两栖生活,用肺呼吸,皮肤可辅助呼吸的动物

答案

答案:D

题目分析:两栖动物是指幼体生活在水中,用鳃呼吸,发育为变态发育,成体既能生活在水中,又能生活在陆地上,用肺呼吸,皮肤辅助呼吸,如青蛙等。既能生活在水中,又能生活在陆地上的动物如龟、扬子鳄等属于爬行动物。故选:D

单项选择题
单项选择题

My Space and other Web sites have unleashed a potent new phenomenon of social networking in cyberspace, (1) at the same time, a growing body of evidence is suggesting that traditional social (2) play a surprisingly powerful and under-recognized role in influencing how people behave.

The latest research comes from Dr. Nicholas A. Christakis, at the Harvard Medical School, and Dr. James H. Fowler, at the University of California at San Diego. The (3) reported last summer that obesity appeared to (4) from one person to another (5) social networks, almost like a virus or a fad. In a follow-up to that provocative research, the team has produced (6) findings about another major health (7) : smoking. In a study published last week in the New England Journal of Medicine, the team found that a person’s decision to (8) the habit is ply affected by (9) other people in their social network quit—even people they do not know. And, surprisingly, entire networks of smokers appear to quit virtually (10)

For (11) of their studies, they (12) of detailed records kept between 1971 and 2003 about 5,124 people who participated in the landmark Framingham Heart Study. Because many of the subjects had ties to the Boston suburb of Framingham, Mass. , many of the participants were (13) somehow—through spouses, neighbors, friends, co-workers—enabling the researchers to study a network that (14) 12,067 people.

Taken together, these studies are (15) a growing recognition that many behaviors are (16) by social networks in (17) that have not been fully understood. And (18) may be possible, the researchers say, to harness the power of these networks for many (19) , such as encouraging safe sex, getting more people to exercise or even (20) crime.

2()

A.resource

B.database

C.communication

D.intranet