题干

一根阻值为R的均匀电阻丝,长为L,横截面积为S,设温度不变,在下列哪些情况下其电阻值仍为R。 [ ]

A:当L不变,S增大一倍时

B:当S不变,L增大一倍时

C:L和S都缩小为原来的1/2

D:当L和横截面的半径都增大一倍时。

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C

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完形填空

     When people think of tigers, they think: strong and dangerous. But now, the big animal is calling for our help.

     There were once eight kinds of   1   in the world, but three died out during the 20th century. In the last 70 years, the   2   of Siberian tigers (东北虎) has gone from as many as 300 to   3   22 somewhere. The Siberian tiger has been   4   dying out completely. If the government doesn't make any efforts, it's quite   5   that there will be no more Siberian tigers in China in ten to twenty years.

     In order to double the number of wild tigers in the   6   ten years, the World Wildlife Fund for Nature has started a program recently. It   7   save wild tigers and put an end to tiger hunting and killing. China, together with twelve other   8  , has joined in.

     Wild animals, such as red deer and wild pigs, are the main   9   of the tigers. The hunting of these animals is the greatest threat(威胁) to tigers. So the most important thing is   10   the animals that tigers eat. To protect the wild tigers, we need to call on more people to stop eating and hunting wild animals.

 1 A. pigs        B. tigers             C. deer              D. lions

 2 A. name       B. kind              C. number           D. type

 3 A. less than    B. more than        C. bigger than       D. larger than

 4A. in need of   B. in danger of      C. in front of  D. in spite of

 5 A. possible     B. impossible   C. necessary         D. unnecessary

 6 A. last        B. next             C. past             D. first

 7 A. aims to     B. used to           C. refuses to         D. aimed to

 8 A. cities        B. provinces          C. countries          D. places

 9 A. friends      B. food               C. members          D. relatives

 10 A. to sell     B. to kill           C. to save           D. to buy