问题 选择题

发生赤潮和水华,会造成鱼类大量死亡,原因是(  )

A.缺氧或中毒

B.缺少食物和氧气

C.缺少阳光和食物

D.缺少氧气和阳光

答案

富营养化是指海水中的营养物质过多,特别是含氮、含磷的无机盐大量增多造成的.大量的生活污水(含氮、磷)和含有大量有机物的工业废水直接排入大海,海洋中的磷、氮等营养盐和铁、锰等微量元素及一些有机化合物迅速增加,这时就出现了“富营养化“现象,过多的营养物质会使海水里藻类植物营养过盛疯狂的生长,出现赤潮现象.

    赤潮形成后,赤潮藻类会产生一些剧毒的毒素,有的毒素毒性与河豚毒素的毒性相当.海洋动物摄食这些藻类后,其毒素会积聚在动物体内,同时大量的藻类植物要进行呼吸消耗氧气,而使得水中缺氧,进而引起鱼虾、贝类等海洋生物大量死亡.

故选:A.

阅读理解

阅读理解。

     A man hated his wife's cat and decided to throw it away.

     One day, he drove it over one mile from his home and left it in a park. But when he got home, he saw

that his wife was playing with the cat.

     The next day he drove the cat about three miles away. He put the cat out of the car and went home.

Driving back his driveway (私人车道), the cat was there already.

     The man keep taking the cat further and further away and the cat would always get home before him.

At last he decided to drive more than ten miles away. He turned right, then left, past a bridge, then right

again and another right until he thought he was far enough from home and left the cat there.

     Hours later the man was still driving home. He was lost! He called home and asked his wife, "Jen, is the

cat there?"

     "Yes," his wife answered, "why do you ask?"

     The man answered, "Put it on the phone. I'm lost and need directions."

1. The first time the man drove out, he ________.

A. sold the cat

B. took the cat home

C. left the cat in the park

2. Which of the following is TRUE?

A. The man liked his wife's cat and often played with it.

B. Every time the man threw the cat away, it came home earlier than the man.

C. The last time the man threw the cat away, it lost its way and didn't come back.

3. Why did the man call home? 

A. Because he was lost.

B. Because he missed his wife very much.

C. Because he wanted to know if the cat was at home.

4. How far away did the man take the cat the last time? 

A. Over 1 mile.

B. About 3 miles.

C. More than 10 miles.

单项选择题