消除散射线的最有效方法是 A．固有滤过 B．缩小照射野 C．增加肢-片距 D．减少曝

下列方法中可以用来进行海水淡化的是

A．过滤法

B．萃取法

C．分液法

D．蒸馏法

下列（）的特征是ⅡA《标准》中描述的“标准”属性。

A．段落1 

B．段落2 

C．段落3 

D．段落4

手提式或移动式磁粉探伤设备的电缆线可制成线圈作为纵向磁化线圈使用。

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.

6（）

A.consequent

B.controversial

C.similar

D.diffident

从论述林木结实规律的角度，林木发育期可分为4个时期，分别是（）、（）、（）和（）。