OSI参考模型中物理层提供了哪些服务

关于辨证的描述正确的是（）

A.通过四诊收集症状、体征等资料

B.分析疾病的原因、性质、部位

C.分析邪正之间的关系

D.概括、判断为某种性质的证

E.以上都是

男，20岁，因墙倒伤及右前胸引起胸痛、呼吸困难，并见反常呼吸运动。x线片示右侧4～7肋骨多处骨折，但无血气胸。急救措施应首先选择

A．镇静止痛
B．输液、输血
C．加压包扎固定
D．内固定
E．给氧

Holding a cell phone against your ear or stalling it in your pocket may be hazardous to your health．

This paraphrases a warning that cell phone; manufacturers include in the small print that is often tossed aside when a new phone is purchased．Apple, for example, doesn’t want iP hones to come closer to you than 1．5 centimeters; Research In Motion, Blackberry’s manufacturer, recommends 2.5 centimeters．

If health issues arise from cell phone use, the implications are huge．Voice calls - Americans chat on cell phones 2．26 trillion minutes annually - generate $109 billion for the wireless carriers．

Devra Davis, an epidemiologist who has worked for the University of Pittsburgh, has published a book about cell phone radiation, "Disconnect." The book surveys scientific research and concludes the question is not settled.

　　Brain cancer is a concern that Ms. Davis examines. Over all, there has not been an increase in its incidence since cell phones arrived. But the average masks an increase in brain cancer in the 20-to-29 age group and a drop for the older population.

　　"Most cancers have multiple causes," she says, but she points to laboratory research that suggests low-energy radiation could damage cells that could possibly lead to cancer.

　　Children are more vulnerable to radiation than adults, Ms. Davis and other scientists point out. Radiation that penetrates only five centimeters into the brain of an adult will reach much deeper into the brains of children because their skulls are thinner and their brains contain more absorptive fluid. No studies have yet been completed on cell phone radiation and children, she says.

　　Henry Lai, a research professor in the bioengineering department at the University of Washington, began laboratory radiation studies in 1980 and found that rats exposed to radiofrequency radiation had damaged DNA in their brains.

　　Ms. Davis recommends using wired headsets or the phone’s speaker. Children should text rather than call, she said, and pregnant women should keep phones away from the abdomen.

小题1:We can infer from the passage that________．

A．Cell phone may do harm to our health if we hold it against our ear or store in our pocket

B．Devra Davis thinks that there are many factors contributing to cancer．

C．The increase in brain cancer in the young adults may have something to do with cell phone

D．Children are more likely to be affected by radiation小题2:According to the passage, how could children avoid being hurt by cell phone radiation?

A．They can keep cell phones away from the abdomen．

B．They can send short massage instead of making phone calls directly．

C．They can pay more attention to the small print on the phone．

D．They should use more advanced cell phones．小题3:From this passage we can learn that．________．

A．American cell phone manufacturers did not give any warning to their customers

B．American cell phone manufacturers benefit greatly from their products

C．Scientists have found the connection between brain cancer and ceil phone

D．Cell phone should be banned because of the increase in brain cancer小题4:In which column can we most probably read this passage?

A．Advanced technology．

B．Entertainment．

C．Science and life．

D．Celebrity．

约束理论认为，建立库存缓冲的目的是防止系统内外的随机波动造成瓶颈出现、等待任务的情况。