阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空白处填入一个适当的词或使用括号中词语的正确形式填空。
The earth
is our home. We must look {#blank#}1{#/blank#} it well. That is to say we must keep the land,
air and water clean.
But man
has been polluting {#blank#}2{#/blank#} earth since he first made a fire. People
washed their clothes in the river and threw dirty things on the ground. Many {#blank#}3{#/blank#} (year) ago, pollution has not so serious {#blank#}4{#/blank#} there were not so many people. When the land
or the river became dirty in one place, man moved to another place. But. now,
there is {#blank#}5{#/blank#} (little)clean air, land and water. Man is {#blank#}6{#/blank#} (pollute) the whole world and there {#blank#}7{#/blank#} neither enough clean air, nor clean land, nor
clean water. More people, more pollution.
Is it
possible to get rid of(解决)pollution?
We are glad to say that people have come to know the {#blank#}8{#/blank#} (dangerous)of pollution and a large number of
them are working hard {#blank#}9{#/blank#} (protect)our earth. One of the {#blank#}10{#/blank#} (good) ways is to stop the pollution.
