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220. Mr. Wang was reading ______ on how to learn a foreign language when someone came to see him.

220. Mr. Wang was reading ______ on how to learn a foreign language when someone came to see him.

A. paper                  B. a piece of paper      C. a paper                   D. a sheet of paper

Mr. Wang was reading ______ on how to learn a foreign language when someone came to see him.

A. paper　　 B. a piece of paper　 C. a paper　 D. a sheet of paper