_ the students are discussing the question

=> The question is being discussed (by the students).

Câu bị động : thì hiện tại tiếp diễn : S+ is/am/are + being + PII (by......)

_ We did the exercises last week

=> The exercise was done last week

Câu bị động : thì quá khứ đơn : S + was/were + PII (by......)

the students are discussing the question

→ the question is being discussed 

Hiện tại tiếp diễn

S + am/is/are + V-ing + O

-->S + am/is/are + being + P2

We did the exercises last week

→ The exercise was done last week

Quá khứ đơn

S + V(ed/Ps) + O

--->S + was/were + P2