Experts have been warning___of the health risks caused by passive smoking.

Scientists are convinced___the positive effect of laughter___physical and mental health.

_______the silence of the pauses,we could hear each other’s breathing and could almost hear our own heartbeats.

Although _______ my opinion,the old professor didn’t come up with his own.

I think he is taking an active part in social work.I agree with you______.

The two sportsmen congratulated each other______winning the match by shaking hands.

--- Why do you suggest we buy a new machine?
--- Because the old one has been damaged ___________.

Elizabeth has already achieved success_____her wildest dreams.

Fred entered without knocking and, very out of breath, sank _______ a chair.

I began to feel _____ in the new school when I saw some families faces.