左心室压上升速率最快是在（） A.等容收缩期 B.快速射血期 C.减慢射血期 D.等

青蛙是变温动物的主要原因是（　　）

A．皮肤裸露

B．体表无羽毛等保温结构

C．食量小，体温不恒定

D．血的输氧能力低

已知二面角α-l-β的大小为30°，m、n为异面直线，m⊥平面α，n⊥平面β，则m、n所成的角为______．

Contrary to common belief, social media websites such as Facebook do not weaken personal ties, they strengthen them in unique ways for different age groups, according to a new study．

The rapid spread of Facebook, which has more than 500 million users worldwide, has prompted concerns about its negative effects, but researchers at the University of Texas have reached a different conclusion．

"Our findings suggest that Facebook is not replacing face-to-face interactions between friends, family and colleagues," said S．Craig Watkins, an associate professor of radio, TV and film who headed the research team．

"In fact, we believe there is sufficient evidence that social media afford opportunities for new expressions of friendship, intimacy and community．"

The researchers questioned 900 college students and recent graduates about how and with whom they interact on Facebook．

More than 60 percent of Facebook users said posting status updates was among the most popular activities, followed by 60 percent who wrote comments on their profile and 49 percent who posted messages and comments to friends．

The researchers also found that although about the same number of men and women use Facebook, they do so in different ways．

"There is a noteworthy difference in aims in how to use a tool like Facebook．We found that for women the content tends to be more affectionate, and （they） are especially interested in using it for connection," said Watkins．

"For men, it's more functional," he added．

Watkins pointed out that, for example, women are more likely to post pictures of social gatherings with friends, while men are more likely to post pictures of hobbies, or post a political or pop-culture related link．

小题1:What's the popular viewpoint of ordinary people about the function of social media websites? They think ____．

A．It is positive to personal ties

B．It has negative effects on personal ties

C．It makes no difference to personal ties

D．It has both good and bad effects to personal ties小题2:What's the meaning of the underlined word in the second paragraph?

A．resulted from

B．had

C．showed

D．produced小题3:What do Facebook users like to do mostly on Facebook? They like to ____．

A．create new expressions of friendship '

B．wrote comments on their profile

C．update their personal statuses

D．post messages and comments to friends小题4:According to the study, ____．

A．Men concentrate more on the functions of Facebook

B．Much more men use Facebook than women

C．Men and women use a tool like Facebook for the same aim

D．Facebook is taking the place of face-to-face interactions between friends

接收“110”报警是一项公安专业工作。 ( )

急性膀胱炎的诊断性检查，宜采用（）。

A.膀胱镜检查

B.细菌学培养加药敏试验

C. * * 分泌物涂片检查

D.前列腺液常规检查

E.前列腺穿刺检查