Why did you plant so many trees— ______ the environment.

th, there’s a man at the front door who says he has news for you ________ vital importance.

Oh, dear! I can’t find my new bracelet. Where on earth did I put it? —What a careless guy. It is on the table______ we had dinner together yesterday.

It is _____ to feel tired after such a long trip.

I’d appreciate________if you would turn out the lights.I’m sleepy.