Health is very _____and every student knows the _____of keeping healthy.
--Will Tom come to our party?--______I’m not sure.
They were all very tired, but ______of them took a rest.
After the hard work, what we want is ______a rest.
You _____keep the water running all the time, because you’re wasting water.
--Ann has finished her homework, hasn’t she?--Yes. She ______it an hour ago.