如图所示的电路中,电源电压恒为4.5V,电压表量程0~3V,电流表量程0~0.6

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问题:

如图所示的电路中,电源电压恒为4.5V,电压表量程0~3V,电流表量程0~0.6A,滑动变阻器规格是“10Ω  1A”,灯泡标有“2.5V  1.25W”;若闭合开关,两电表示数均不超过所选的量程,灯泡两端电压不允许超过额定电压,不考虑灯丝电阻的变化.则下列说法正确的是(    )

A.电流表的示数变化范围0.3A~0.6A

B.电压表的示数变化范围是1.5V~2.5V

C.滑动变阻器允许调节的阻值范围是2.5Ω~10Ω

D.该电路最大功率是2.7W

考点:欧姆定律及其应用
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“宽是长的几分之几”与“宽与长的比”,意义相同,结果表达形不同.______.

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The rat is named Lola and she’s at the top of her class of risk-running animals being trained to smell out landmines (地雷) in Colombia, home to the world’s highest number of mine-related deaths and injuries last year. Of the victims, many are children who died in the accidents while walking to school or playing in the countryside.

The smartest rat among the first six that the government is teaching to locate landmines equipment planted by rebels(叛乱者) has a 90 percent success rate in locating landmines material in her lab training.

Police animal trainers, tired of seeing their landmines-smelling dogs blown up by stepping on mines, hope the white-furred, pink-eyed creature will lead her classmates through coming open field tests and then into the country mine fields before the end of the year. It takes about 400 grams of pressure to detonate (引爆) a mine while Lola only weighs about 220 grams. “The dogs can easily set off the landmines, sometimes killing people nearby,” they said.

Police animal trainer Jose Pineda says that rats have more sensitive noses than dogs, which should allow them to better smell out mines in difficult terrain (地形).

Plus, it takes the police about six months to train mine-smelling dogs. Training the rats is expected to take about half that time once the program is established.

Trainers think that they are much smarter than the dogs. The second-best scorer in the laboratory is Lucrecia, with an 83 percent success rate. Males, such as one named   Runcho, have fallen behind until now but may do better in the coming field tests. Pineda said that the next step of training will present new challenges to the rats as they are sure to meet distractions (分心的事) in the open.

小题1:What do the underlined words “the accidents” in the first paragraph mean?

A.Children were shot while playing outside.

B.A buried landmine was walked on and set off.

C.A rebel blew up a landmine and killed children.

D.Children got hurt in traffic accidents on the way to school.小题2:Which of the following is NOT a reason why rats are chosen to find buried landmines?

A.They have a good sense of smell.

B.They are too light to set off buried landmines.

C.They can smell all kinds of explosive materials.

D.They cost people less time in terms of training小题3:What can we learn from the last paragraph?

A.Rats will perform as well in the open air as in the lab.

B.Until now, female rats are better than the male ones.

C.Trainers should have chosen only female rats for the program.

D.Because they are foolish, dogs are not preferred for the program.小题4:What would be the best title for the passage?

A.Dogs Bring Peace to the People in Colombia

B.Colombia Develops a New Way to Reduce Deaths

C.Buried Landmines are a Great Danger to Colombians

D.Colombian Police Train Rats to Sniff Out Landmines

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储蓄函数

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加重肝脏吞噬、免疫及解毒功能的负担,引起机体代谢增高与氧耗量增加而诱发肝性脑病

A.药物不恰当使用
B.上消化道出血
C.高蛋白饮食
D.感染
E.便秘

题型:选择题

红外定量分析方法有()法

A、示差

B、工作曲线

C、内标

D、双波长

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