Hundreds of years ago，life was much harder than it is today.People didn't have modern machines.There （1）

was

was

（be）no modern machine，either.
   Life today has brought new problems.One of the （2）

biggest

biggest

（ big） is pollution.Water pollution has made our rivers and lakes dirty.It kills our fish and pollutes our drinking water.Noise pollution makes us talk louder and become angry more （3）

easily

easily

（ easy）.Air pollution is the most serious kind of pollution.It is bad （4）

for

for

all living creatures，
   Cars，planes and factories all pollute our air every day.Sometimes the （5）

polluted

polluted

/p??lu?t?d/air is so thick that it is like a quilt（被子） over a city.This kind of quilt is called smog（霧霾）
   Many （6）

countries

countries

/'k?ntriz/ are passing laws to fight against pollution.Factories must now clean their water before it is thrown away （7）

and

and

they mustn't release（釋放） dirty smoke into the air.We can do many other things to protect the environment.We can put rubbish in the dustbin but not throw it on （8）

the

the

ground.We can go to work by bus or with （9）

our

our

/'a??/ friends in the same car.If there are fewer people（10）

driving

driving

（ drive） on the road，there will be less pollution Rules are not enough，however.Every person must help to fight against pollution.