Long time ago, our world was very beautiful. There were trees, flowers and rivers. It was very clean and tidy. 1 . We are living in a polluted environment, which is bad for out earth. 2 .The public has been calling for actions against pollution. Scientists have told us to protect out environment, 3 .
The earth is our only home. We should make it comfortable for ourselves and for our children in the future. Now nearly all of the countries are trying their best to stop pollution. Although they have done much, the progress is slow, 4 . No matter how difficult it is, we should try our best to fight against pollution. By working together, 5 .
根据短文内容，从方框中选出能填入空白处的最佳选项，补全短文。（5分）
小题1:C
小题2:A
小题3:D
小题4:E
小题5:B
题目分析:
小题1:上文介绍了我们的世界很美好,下文说我们生活在一个污染的环境里,故此处需要一个转折性的句子,选C.but,但是.
小题2:结合下文公众已经号召采取行动应对污染,可知选A,人们真的很担心这个问题.
小题3:结合上文科学家告诉我们保护我们的环境,可知选D,否则污染会变得越来越严重.
小题4:结合上文进程很慢和下文不管它有多么困难,可知选E,在我们拥有一个整洁的世界之前还有一条很长的路要走.
小题5:结合上文,通过一起努力,可知选B,我相信……
点评：本文介绍了我们的世界污染越来越严重，号召我们每个人都行动起来，保护我们的环境。本文看起来较难，但是因为五个选项只给了五个答案，故我们答题中可采用排除法，由易到难，完成全文。
要求：根据上述资料，回答下列问题。