The old man grew quite curious and replied: “That may be. If a fish can survive in water as dirty as this, it must have a lot of resistance. So it wouldn’t be too strange if such fish had medicinal benefits.”

    It was clear he was just passing by, so I answered: “Yeah, survival of the fittest. Fish that adapt can survive, just like us humans.”

    He kept talking to me and didn’t want to leave. He wanted to see whether or not I would catch the small fish with medicinal benefits.

21.The text is mainly about ____.

A. a research report about pollution.               B. an exciting experience of fishing.

C. an experience of doing research on pollution          D. an unforgettable talk with an old man.

22. What is the writer of the text most probably?

A. A newspaper reporter.                                         B. A researcher about pollution.

C. A fisherman.                                               D. A worker of the textile mill.