例∶-What is he doing?他正在做什么? -He is running.他正在跑。 (2)当主语为第三人称复数时∶问句∶ What are they doing? 答语∶ They are+动词-ing形式(singing,playing,swimming.)(+其他) 例∶ -What are they doing?他们/她们正在做什么? -They are waiting for...