问题 选择题

十九世纪初,法国科学家库图瓦正在家中做实验,一只猫把盛装海藻灰溶液和硫酸溶液的瓶子都碰翻了,他看到了一个奇异的现象:打翻在地的混合液里产生了一种紫色蒸气,气味十分难闻、呛鼻,而且紫色蒸气遇冷物体后变为紫黑色闪着金属光泽的晶体.库图瓦又做了许多实验,终于弄明白这种气体是一种新发现的元素,这种元素是(  )

A.碘

B.碳

C.铜

D.汞

答案

碘为紫黑色固体,受热容易升华得到紫色的蒸气;碳为黑色固体,而铜为亮红色的固体并且难以在较低的温度下变为气体,汞在常温下是银白色的液体,所以通过对四种物质的分析,结合题给的信息可以知道,只有碘的性质与题给的物质的性质相符合,所以选项A是正确的.

故选A.

单项选择题

阅读下面短文,掌握其大意,从每题所给的A、B、C、D四个选项中,选出最佳选项,并在答题卡上讲该项涂黑。

A Race Against Death

It was a cold January in 1925 in North Alaska. The town was cut off from the rest of the world due to heavy snow.

On the 20th of that month, Dr.Welch   36   a Sick boy, Billy, and knew he had diphtheria, a deadly infectious(传染的)disease mainly affecting children. The children of Nome would be  37  if it struck the town. Dr.Welch needed medicine as soon as possible to stop other kids from getting sick.   38  , the closest supply was over 1,000 miles away, in Anchorage.

How could the medicine get to Nome? The town`s  39  was already full of ice, so it couldn`t come by ship. Cars and horses couldn`t travel on the   40  roads. Jet airplanes and big trucks didn`t exist yet.

41  January 26, Billy and three other children had died. Twemty more were   42  . Nome`s town officials came up with a(n)  43  . They would have the medicine sent by   44  from Anchorage to Nenana. From there, dogeled(狗拉雪橇)drivers—known as “mushers”—would   45  it to Nome in a relay(接力).

The race began on January 27. The first musher, Shannon, picked up the medicine from the train at Nenana and rode all night.  46  he handed the medicine to the next musher, Shannon`s face was black from the extreme cold.

On January 31, a musher named Seppala had to   47  a frozen body of water called Norton Sound .It was the most  48  part of the journey. Norton Sound was covered with ice,which could sometimes break up without warning.If that happened,Seppala might fall into the icy water below.He would  49  ,and so would the sick children of  Nome.But  Seppala made it across.

A huge snowstorm hit on February 1.Amusher  named Kaasen had to brave this storm.At one point,huge piles of sonw blocked his 50  .He had to leave the trail (雪橇痕迹)to get around them.Conditions were so bad that it was impossible for him to  51  the trail again. The only hope was Balto,Kaasen’s lead dog, Balto put his nose to the ground, 5 2  to find the smell of other dogs that had traveled on the trail.If  Balto failed,it would mean disaster for Nome.The minutes passed by.Suddenly, Balto began to  53  .He had foung the trail

At 5:30 am on February 2, Kaasen and his dog  54  in Nome. Within minutes,Dr.Welch had the medicine.He quickly gave it to the sick children.All of them recoverd.

Nome had been  55  .

36()

A.examined

B.warned

C.interviewed

D.cured

问答题 简答题