I think you should pay attention to the lessons in class. (You)

→ If I _______________________________________ the lessons in class.

I worry about the (destruct) _______ effect that violent films may have on children.

(Mystery) _______, the light came on, although no one was near the switch.

There's not enough (interact) _______ between the management and the workers.

Perhaps we would go to Hanoi to visit our friends. (Went)

→ If we ________________________________________ visit our friends.

They should give up smoking to protect their health. (would)

→ If they ___________________________________ improve their health.

Children are encouraged to take an (investigate) _______ approach to learning.