21. While he was investigating ways to improve the telescope, Newton made ________ discovery which completely changed ________ man’s understanding of color.

  A. a; £¯                             B. a; the                   C. £¯; the                D. the£»a

22. In many states of America, a neighbor may ______ you with playing your radio too loudly.

A. charge                B. blame              C. punish                D. scold