It was she that ________a sharp whistle, which makes ________possible for us to catch the thief.

Why don’t you drive to work today—Sometimes riding is even thandriving during the busy traffic time.

ore and more forests _____, manyanimals are facing the danger of dying out.

He hasn’t slept at all for three days________ he is tired out[ ]

I think it’s_________ useful advice，so I will always remember it．