问题 单项选择题

按照材料的微观组成分类,土木工程中常用的石蜡属于()。

A.原子晶体

B.金属晶体

C.离子晶体

D.分子晶体

答案

参考答案:D

解析:

[点评] 本题要点在于材料的组成与结构部分,涉及材料的微观组成,原子晶体为由中性原子直接构成的晶体,其质点之间主要依靠原子间的共价键相互结合为整体;金属晶体的金属原子团主要依靠自由电子的库伦引力构成晶体;离子晶体主要由正、负离子依靠离子键的结合引力构成晶体;分子晶体的分子或分子团依靠非对称的电子极化引力而形成晶体。本题中石蜡依靠范德华力构成分子晶体。

阅读理解

The Pacific island nation of Nauru used to be a beautiful place. Now it is an ecological(生态的) disaster area. Nauru’s heartbreaking story could have one good consequence — other countries might learn from its mistakes.

For thousands of years, Polynesian people lived the remote island of Nauru, far from western civilization. The first European to arrive was John Fearn in 1798. He was the British captain of the Hunter, a whaling ship. He called the island Pleasant Island.

However, because it was very remote, Nauru had little communication with Europeans at first. The whaling ships and other traders began to visit, bringing guns and alcohol. These elements destroyed the social balance of the twelve family groups on the island. A ten-year civil war started, which reduced the population from 1,400 to 900.

Nauru’s real troubles began in 1899 when a British mining company discovered phosphate (磷酸盐)on the island. In fact, it found that the island of Nauru was nearly all phosphate, which a very important fertilizer for farming. The company began mining the phosphate.

A phosphate mine is not a hole in the ground; it is a strip mine(带状矿). When a company strip-mines, it removes the top layer(层) of soil. Then it takes away the material it wants. Strip mining totally destroys the land. Gradually, the lovely island of Nauru started to look like the moon.

In 1968, Nauru became one of the richest countries in the world. Every year the government received millions and millions of dollars for its phosphate.

Unfortunately, the leaders invested the money unwisely and lost millions of dollars. In addition, they used millions more dollars for personal expenses. Soon people realized that they had a terrible problem — their phosphate was running out. Ninety percent of their island was destroyed and they had nothing. By 2000, Nauru was financially ruined. Experts say that it would take approximately $433,600,000 and more than 20 years to repair the island. This will probably never happen.

小题1:What might be the author’s purpose in writing the text?

A.To seek help for Nauru’s problems.

B.To give a warning to other countries.

C.To show the importance of money.

D.To tell a heartbreaking story of a war.小题2:What was Nauru like before the Europeans came?

A.Rich and powerful.

B.Modern and open.

C.Peaceful and attractive.

D.Greedy and aggressive.小题3:The ecological disaster in Nauru resulted from           .

A.soil pollution

B.phosphate over mining

C.farming activity

D.whale hunting小题4:Which of the following was a cause of Nauru’s financial problem?

A.Its leaders misused the money.

B.It spent too much repairing the island.

C.Its phosphate mining cost much money.

D.It lost millions of dollars in the civil war.小题5:What can we learn about Nauru from the last paragraph?

A.The phosphate mines were destroyed.

B.The leaders will take the experts’ words seriously.

C.The island was abandoned by the Nauruans.

D.The ecological damage is difficult to repair.

判断题