问题 问答题 简答题

高压架空配电线路的主要特点是有那些?

答案

参考答案:

①支接点较少;

②在档距大、导线张力高的线路上安装有导线防震装置;

③由于电压等级不很高,一般不采用分裂导线;

④在大气过电压保护方面,110kV电压等级的架空配电线路通常与超高压输电线路一样采用全线避雷保护,其他较低电压等级的线路则根据各国的不同标准,有的采用全线避雷保护,有的则在变电所进行1~2km内架设避雷线保护,我国则采用进线段架设避雷线保护;

⑤在城市配电网中,较低电压等级的高压架空配电线路往往与中、低压架空配电线路同杆架设,而在110kV电压等级的线路下,一般不再安排其他电压等级的线路同杆架设。

阅读理解

London—coffee protects mice from radiation and could get the same way in humans, according to Indian scientists.

Scientist at India’s Bhabha Atomic Research Center discovered that mice injected with caffeine (咖啡因)remained alive after high doses(剂量)of normally lethal radiation.

Although the study was limited to animals, Kachadillilli George, head of the research team, believes the findings could have implications (something suggested )  for humans .

“It does suggest that coffee might have some beneficial effects in protecting against radiation,” he told New Scientist magazine late last month.

George and his team injected 471 mice with caffeine and left them uncovered to 7.5 grays of gamma radiation(伽玛射线),enough to kill most mice. But 25 days later 70 percent of the mice that had received 80 milligrams(毫克)of caffeine per kilogram of body weight were still alive.

On the contrary all 196 mice that had been left uncovered to the same radiation but had not been given any caffeine died.

小题1:George and his team drew the conclusion from    .

A.the magazine

B.their invention

C.the experiment

D.their experience小题2:From the news, we know     can be protected from radiation.

A.both mice and humans

B.only mice

C.only humans

D.neither humans nor mice小题3:From paragraph 5, we know 30 percent of the mice died 25 days later. The reason was probably that     .

A.these mice had been given only 80 milligrams of caffeine

B.these mice hadn’t been injected with caffeine

C.these mice were very big and strong

D.these mice hadn’t been given enough caffeine小题4:Which is the best title of the article?

A.Human and Mice

B.New Radiation Defense—Coffee

C.Deadly Radiation—Gamma Radiation

D.Mice Died of Caffeine小题5:In paragraph 2,the underlined word “ lethal ”means   .

A.causing death

B.lively

C.exciting

D.rich

单项选择题 共用题干题