问题 选择题

磁性是物质的一种普遍属性,大到宇宙中的星球,小到电子、质子等微观粒子几乎都会呈现出磁性.地球就是一个巨大的磁体,其表面附近的磁感应强度约为3×10-5~5×10-5 T,甚至一些生物体内也会含有微量强磁性物质如Fe3O4.研究表明:鸽子正是利用体内所含有的微量强磁性物质在地磁场中所受的作用来帮助辨别方向的.如果在鸽子的身上绑一块永磁体材料,且其附近的磁感应强度比地磁场更强,则(   )

A.鸽子仍能辨别方向过

B.鸽子更容易辨别方向

C.鸽子会迷失方向

D.不能确定鸽子是否会迷失方向

答案

C

题目分析:地磁的北极在地理的南极附近,故电磁场在地球外部是地理的南极指向地理的北极,故鸽子体内的小磁针的N极受力方向就是地球的北极方向,而在鸽子的身上缚一块永磁体材料后鸽子周围的磁场不再是电磁场,故鸽子会迷失方向.鸽子正是利用体内所含有微量强磁性物质在地磁场中所受的作用来帮助它辨别方向的,即其体内所含有微量强磁性物质相当于一个小磁针,小磁针的N极受力方向就是地球的北极方向,而在鸽子的身上缚一块永磁体材料后严重干扰了电磁场,使鸽子体内的小磁针N极受力的方向不再是地球的北极,这样会使鸽子迷失方向,故C正确.

故选:C

阅读理解

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According to official statistics released by the Chinese government, China is expected to run out of water around the year 2030. In its directive on water use, the State Council (国务院) has stated, “Taking into full account water-saving, by 2030 our country’s water use will reach or approach the total volume of exploitable water resources (可利用的水资源总量), and the drought-fighting situation will be increasingly serious.” Such statements are certainly serious, and every man, woman and child in China must consider the situation and how it relates to their lives.

So, will China run out of water completely? The news is not all bad. Although there are serious concerns, there are some reasons to be hopeful. One of the simplest is just to consider that China has had a long history of water problems. From flooding to drought, balancing water needs has always been an issue in China; it is something that many public projects are already addressing. Some of these projects need time before their long-term value can be properly seen, but there is reason to hope that they will prove useful.

Another reason for hope lies in what seems at first to be a terrible fact: nearly 70% of China’s water is so contaminated that it is not only unsuitable for drinking but is also not useful for individual purposes. How can this be good news? Well, in recent years, the terrible situation has motivated the government and the public to become more and more committed to cleaning up these contaminated sources. Several projects have already been successful in partially cleaning these water sources. As this commitment increases, more and more of China’s water is being cleaned and made available for use.

Finally, the international community, particularly NGOs (Non Government Organizations) and the corporate community, have begun to focus on ways to help China stretch its limited water resources. Several business and NGOs are already studying the issue and investing in solutions.

It is certainly important for everyone in China to understand the situation and to take part in conserving water. Thankfully, however, the situation is not hopeless. Through the cooperation of the government, the people, NGOs and business, China can continue to find the water it needs.

72. What does the first paragraph tell us?

A. China is seriously short of water now.’

B. We still have enough water for drink and use.

C. China will be faced with serious water shortage in two decades.

D. We needn’t consider the situation for the moment.

73. Which of the following reasons to be hopeful is not mentioned?

A. Many in the international and corporate community have begun to help China.

B. China has dealt with many water problems.

C. The government and the public are becoming more and more committed to cleaning up the contaminated sources.

D. The Chinese have enough confidence and courage to overcome the difficulty.

74. Which of the following can replace the underlined word contaminated in Paragraph 3?

A. cleaned           B. wasted           C. polluted            D. purified

75. Which of the following statements is TRUE according to this passage?

A. The international community and the corporate community have begun to help China develop it limited water resources.

B. All China’s water is so contaminated that it is unsuitable for both drinking and industrial purposes.

C. Several business and NGOs had already studied the issue and invested in solutions.

D. There is no hope for China to find the water it needs.

单项选择题