题干

埃及的阿斯旺大坝建成后,尽管改善了电力和灌溉条件,取得了明显的经济效益,但巨大的水库沿岸水草丛生,使血吸虫发病率高达80%~100%,尼罗河下游农田失去了肥源等,这说明该工程( )

A:经济效益和生态效益良好

B:在一定程度上破坏了生态平衡

C:维持了原来的生态平衡 

D:使生态系统的结构变得复杂

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答案(点此获取答案解析)

B

同类题5

根据短文理解,选择正确答案。

    In choosing a friend, one should be very careful. A good friend can help you study. You can have fun together and make each other happy. Sometimes you will meet fair­weather friends. They will be with you as long as you have money or luck,but when you are down, they will run away. How do I know when I have found a good friend? I look for certain qualities of character,especially understanding, honesty and reliability(信任).

    Above all else, I look for understanding in a friend. A good friend tries to understand how another person is feeling. He is not quick to judge. Instead, he tries to learn from others. He puts himself in the other person's place, and he tries to think of ways to be helpful. He is also a good listener.

    At the same time, however, a good friend is honest. He does not look for faults in others. He notices their good points. In short, a friend will try to understand me and accept me.

    Another quality of a friend is reliability. I can always depend on a good friend. If he tells me he will meet me somewhere at a certain time, I can be sure that he will be there. If I need a favor,he will do his best to help me. If I am in trouble, he will not run away from me.

    There is a fourth quality that makes a friend special. A special friend is someone with whom we can have fun. We should enjoy our lives, and we would enjoy our friendship. That is why I especially like friends who are fun to be with. A good friend likes the same things I like. We share experience and learn from each other. A good friend has a good sense of humor too. He likes to laugh with me. That is how we share in the joy of being friends. And I know that he is looking for the same quality in me.

    When I meet someone who is reliable, honest, and understanding,I know I've found a friend!