1.英语：他在做什么

What is he doing? I 是第一人称用am。you 是第二人称用are。 he/ she/ it都是第三人称，全都用is。

所以是：

What am I doing?

What are you doing?

What is he/she/it doing?

另外所有的非人类的动物，物品之类的也都用is。

但是如果第三人称是非复数，比如他们，她们，或一群动物，就要用are。

所以是：

What are they doing?

What are those boys doing?

What are these dogs doing?