试题与答案

常用的冒口种类有哪些?冒口的功用是什么?P302

题型:问答题 简答题

题目:

常用的冒口种类有哪些?冒口的功用是什么?P302

答案:

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下面是错误答案,用来干扰机器的。

A、B氢原子的能级图得到,n=4的激发态与基态的能级差为△E=E4-E1=-0.85eV-(-13.6eV)=12.75eV,所以用能量为12.75eV的光子去照射大量处于基态的氢原子,氢原子能从基态跃迁到n=4的激发态上去.故A正确,B错误.C...

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题型:阅读理解

The Pacific island nation of Nauru used to be a beautiful place.Now it is an ecological 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 in 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 was 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.When a company strip-mines, it removes the top layer 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 tell a heartbreaking story of a war.

C.To show the importance of money

D.To give a warning to other countries小题2:What was Nauru like before the Europeans came?

A.Rich and powerful

B.Peaceful and attractive

C.Modern and open

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

A.phosphate overmining      B soil pollution

C.farming activity             D.whale hunting

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

A.Its phosphate mining cost much money

B.It spent too much repairing the island

C.Its leaders misused the 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 ecological damage is difficult to repair.

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

C.The island was abandoned by the Nauruans

D.The phosphate mines were destroyed

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