Question

We should keep the environment clean

--> The environment________________

Answer 1

We should keep the environment clean

--> The environment______should be cleaned____

Answer 2

--> The environment should be kept clean by us.

Answer 3

We should keep the environment clean

--> The environment should be kept clean. (câu bị động vs động từ khiếm khuyết: S + modal verb + be + Vpp + (by + O) )

Answer 4

We should keep the environment clean--> The environment clean should be kept