听第10段材料，回答第17至20题。

17．What is wrong with the lake?

A．Its color is strange．

B．There are not enough fish there．

C．A chemical pollution happened there．

18．What probably caused the trouble?

A．People's action．

B．The weather．

C．Fish．

19．What will listeners probably hear next?

A．Sports news．

B．Update information on the lake．

C．The weather report．

20．What does the report mainly talk about?

A．The pollution of the lake．

B．The colour change of the lake．

C．Warnings to children．

第二部分 阅读理解(共两节，满分40分)

第一节(共15小题；每小题2分，满分30分)

阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项。

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