Onthe40thEarthDay,DrWanggaveusatalkontheimportanceof   ...

問題詳情：

On the 40th Earth Day, Dr Wang gave us a talk on the importance of        the earth.

A. practicing               B. preventing               C. polluting                 D. protecting

【回答】

D

知識點：動詞和動詞短語

題型：選擇題