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

问题补充：

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

答案：

A. paper

B. a piece of paper

C. a paper

D. a sheet of paper

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