answer: The teacher asked the students what they were doing then.

`-` Câu gián tiếp dạng Wh_question:

S + asked + O + Wh_ +  S +  V(lùi thì)

`-` then `-` now

`-` HTTD `-` QKTD.

Answer: The teacher asked the students what they were doing then.

`@` Câu tường thuật Wh-questions:

`-` S + asked/wondered/wanted to know + (O) + wh-word + S + V(lùi thì)

`-` Lùi thì: HTTD `->` QKTD (was/were Ving)

`-` Đổi ngôi: we `->` they

`-` now `->` then