用所给的词的适当形式填空,有两项多余.

用所给的词的适当形式填空,有两项多余.
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large small in problem grow busy decrease
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The poputation problem is one of the greatest__1__of the world today.China has the__2__number of population in the world.If the population grows too fast,there will be many serious problems.For example,people wil not have enough food to eat or enough houses to live__3__.The traffic will be__4__.People will cut more trees.There willnot be enough space to stand in.So we should do our best to stop the population from__5__too fast.
1._____ 2._____ 3._____ 4._____ 5._____