He is not doing his homework; he is sleeping.

他没在做作业，他在睡觉。

同一单元的其他句子

• I am watching TV in the living room.我正在客厅看电视。
• She is reading a book about animals.她正在读一本关于动物的书。
• They are playing basketball outside now.他们现在正在外面打篮球。
• Are you listening to music? Yes, I am.你正在听音乐吗？是的，我在听。
• We are having dinner at the moment.我们此刻正在吃晚饭。