问题 单项选择题

主要用于易燃、易爆场所中探测可燃气体的浓度,一般调整在爆炸浓度下限的1/5~1/6时动作报警的是(),这是一种极具发展前途的火灾探测器。

A.感烟火灾探测器

B.感温火灾探测器

C.感光火灾探测器

D.气体火灾探测器

答案

参考答案:D

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.

1()

A.so

B.but

C.as

D.although