如图所示电路中,电源电动势为E,线圈L的电阻不计。以下判断正确的是 ( )

题型:选择题

问题:

如图所示电路中,电源电动势为E,线圈L的电阻不计。以下判断正确的是  (    )  

A.闭合S瞬间,R1R2中电流强度大小相等

B.闭合S,稳定后,R1中电流强度为零

C.断开S的瞬间,R1R2中电流立即变为零

D.断开S的瞬间,R1中电流方向向右,R2中电流方向向左

考点:电感器对交变电流的作用电容器对交变电流的作用
题型:选择题
在272÷34中,把34看作30进行试商,会出现(  )
A.初商偏大B.初商偏小C.初商正好
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急性肺水肿的特征性表现是()。

A.端坐呼吸

B.咳粉红色泡沫痰

C.刺激性咳嗽

D.口唇发绀

E.奇脉

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适于室温保存的菌种()

A.真菌

B.霍乱弧菌

C.铜绿假单胞菌

D.粪产碱杆菌

E.脑膜炎奈瑟菌

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五.任务型阅读(10分)
Could your cellphone give you cancer? Whether it could or not, some people are worrying about the possibility that phones, powerlines and wi-fi (路由器) could be responsible for a range of illnesses, from rashes to brain tumours.
For example, Camilla Rees, 48, a former investment banker in the US, moved out of her apartment in San Francisco because of the radiation coming from next door. Rees told the Los Angeles Times that when her neighbors moved in and installed a wi-fi router she lost her ability to think clearly. “I would wake up dizzy in the morning. I’d fall to the floor. I had to leave to escape that nightmare,” she said. Since then, she’s been on a campaign against low-level electromagnetic fields, or EMFs(低频电磁场).
And she’s not alone. Millions of people say they suffer from headaches, depression, nausea and rashes when they’re too close to cellphones or other sources of EMFs.
Although the World Health Organization has officially declared that EMFs seem to pose little threat, governments are still concerned. In fact, last April, the European Parliament called for countries to take steps to reduce exposure to EMFs. The city of San Francisco and the state of Maine are currently considering requiring cancer-warning labels on cellphones. 
If these fears are reasonable, then perhaps we should all be worried about the amount of time we spend talking on our phones or plugging into wi-fi hotpots.
Some say there is evidence to support the growing anxieties. David Carpenter, a professor of environmental health sciences at the University at Albany, in New York, thinks there’s a greater than 95% chance that power lines can cause childhood leukemia. Also there’s a greater than 90% chance that cellphones can cause brain tumours.
But others believe these concerns are unreasonable paranoia (猜疑). Dr Martha Linet, the head of radiation epidemiology at the US National Cancer Institute, has looked at the same research as Carpenter but has reached a different conclusion. “I don’t support warning labels for cellphones,” said Linet. “We don't have the evidence that there’s much danger.”
Studies so far suggest a weak connection between EMFs and illness — so weak that it might not exist at all. A multinational investigation of cellphones and brain cancer, in 13 countries outside the US, has been underway for several years. It’s funded in part by the European Union, in part by a cellphone industry group.
According to Robert Park, a professor of physics at the University of Maryland in the US, the magnetic waves aren’t nearly powerful enough to break apart DNA, which is how known threats, such as UV rays and X-rays, cause cancer.
Perhaps it’s just psychological. Some experts find that the electro-sensitivity syndrome seems to be similar to chemical sensitivity syndrome, which is a condition that’s considered to be psychological.
Whether EMFs are harmful or not, a break in the countryside, without the cellphone, would probably be good for all of us.
Title: Could cellphones give you cancer?
Key points
Supporting details
Cellphones are (71)______ to use
● Some people think it (72)______ for cellphones to cause cancer.
● Camilla Rees got ill after his neighbor installed a wi-fi router.
● Millions of people have the (73) _______ problems as Camilla.
● Some evidence supports people’s anxieties.
Cellphones are safe
to use
● Some believe that these concerns are just paranoia.
● So far, studies show that there isn’t much (74)______ between EMFs and illness.
● Robert Park thinks that the magnetic waves aren’t (75)_______ enough to destroy DNA.
● It’s just for (76)_______ reasons that people feel ill when they use cellphones.
Attitudes and (77)______
● Some governments are (78)_______ about the safety of cellphones or EMFs.
● The author thinks that we should(79)_______ the chance of talking on the phone or spend more time in the(80)_____ areas without cellphones.
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在土壤有机质分解转化及土壤团粒结构形成过程中,起主要作用的一类生物是()。

A.植物

B.原生动物

C.节肢动物

D.微生物

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