题目

下列关于生态系统中物质循环和能量流动的叙述，正确的是 A．富营养化水体出现蓝藻水华的现象，可以说明能量流动的特点 B．生态系统中能量的初始来源只有太阳能 C．食物链各营养级中10%~20%的能量会被分解者利用 D．无机环境中的物质可以通过多种途径被生物群落反复利用 答案：DA In the year 2050,there will be different kinds of materials (材料) for clothes. Special materials will keep the clothes clean for ever. They will never get dirty or wear out. We will have less work because we won't have to wash them. So we can save water and money. And children won't worry about what to wear to school every day. They won't go to school. They'll stay at home in front of their computers to study. They can wear their favourite " Saturday clothes" every day. It will be fun. Do you think so? What do you think school clothes and school life will be like in 2050?(   ) 21. Maybe we wash clothes in the year 2050.   A. didn't   B. needn't   C. mustn't   D. won't be allowed to(   ) 22. Why won't the children go to school?   A. Because they'llplay at home.   B. Because they hate to go to school.   C. Because they'll study on the Internet.   D. Because they'll wash clothes to make money.(   ) 23. Will the clothes get dirty in the year 2050?   A. No,it won't.   B. Yes,they will.   C. Yes,it will.   D. No,they won't.(   ) 24. In the year 2050,the clothes will not for ever.   A. wear out or get dirty   B. wear well   C. be thinner and thinner   D. be fantastic(   ) 25. From the passage,which of the follow?ing is NOT true?   A. There will be different kinds of ma?terials for clothes.   B. The children can wear their favourite clothes.   C. The children always worry about what to wear.   D. The children can study at home in front of their computers.