— _______ may I keep these books?— Twice a week.
.--Look, there are ______number of ducks swimming in the river. --Yes. ______number of them is over ten.
--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.