请仔细研读下面这段课文，并依据各自所提出的问题完成下列各题

小明同学说：“我爸爸说在他小时后，村边的小河里有许多水草、虾、鱼和鸭，河岸岸边长满了青草和大槐树．爷爷常割草喂鱼喂猪喂牛，有时也捕些鱼和鸭来改善生活．可是现在河里的鱼、虾、鸭几乎不见了．”这与环境的变化有什么关系吗？

    Reading is a good habit, but the problem is there's too much to read these days and too little time to read every word of it. There are hundreds of skills to help you read more in less time. Here are two skills that I think are especially good.
    Preview — if it's long and hard. Previewing is especially useful for getting a general idea of heavy reading like long magazine articles and business reports.
    Here's how to preview.
    Read the first two paragraphs and the last two paragraphs carefully.
    Then read only the first sentence of the other paragraphs.
    Previewing doesn't give you all the details. It keeps you from spending time on things you don't really want － or need － or read.
    Skim － if it's short and simple. Skimming is a good way to get a general idea of light reading like popular magazines or the sports and    entertainment of your daily paper.
    Here's how to skim.
    Get your eyes to move fast. Sweep them across each line.
    Pick up only a few key words in each line.
    Everybody skims differently. You and I may not pick up the same words when we skim the same piece, but we'll get a similar idea of what it's all about.

    有这么一个传说，古时候，天上有10个太阳，晒得地面寸草不生。人们热得受不了，就找一个箭法很好的人射掉9个，只留下一个，地面上才不那么热了。其实，太阳离我们有1.5亿公里远。到太阳上去，如果步行，日夜不停地走，差不多要走3500年；就是坐飞机，也要飞二十几年。这么远，箭哪能射得到呢？

    我们看到太阳，觉得它并不大，实际上它大得很， 130万个地球才能抵得上一个太阳，因为太阳离地球太远了，所以我们看上去只有一个盘子那么大。

    太阳会发光，会发热，是个大火球。太阳的温度很高，表面温度有6000摄氏度，就是钢铁碰到它，也会变成汽；中心温度估计是表面温度的2500倍。

陆游在《老学庵笔记》中说：“毫州出轻纱，举之若无，裁以为衣，真若烟霞。一州唯两家能织，相与世世为婚姻，惧他人家得其法也。”上述材料表明（    ）