Hundreds of years ago, life was much harder than it is today. People didn’t have modern machines. There was no modern medicine, either.

Life today has brought new problems.

One of the biggest problems is pollution. Water pollution has made our rivers and lakes dirty. It killed our fish and _____a_____ our drinking water. ____b_____  pollution makes us talk louder and become angry more easily. Air pollution is the most serious kind of pollution. It’s hard to all the living things in the world.

Cars, planes and factories all pollute our air every day, （2）sometimes the polluted air is so thick that it is like a quilt(被子) over a city. This kind of quilt is called smog.

Many countries are making rules to flight pollution. Factories must now clean their water before it is poured away, they mustn’t blow dirty smoke into the air.

We need to do many other things. We can put waste things in the dustbin and not throw it on the ground. We can go to work by bus or with our friends in the same car, (3)如果开车的人少了，空气污染就少了。

1. 在横线上填入适当的单词 a.____________   b. _____________.(每空一词)

2. 将句子(2)译成汉语___________________________________________________________

3. 将句子(3)译成英语___________________________________________________________

4. 找出Dirty water must be stopped from dumping into the river. 的同义句.

5. 找出或写出能概括本文大意的句子。