---Who is the tallest boy? ---It ______ be John. John is of medium height.
David often helps Sandy ___ her Maths, he shares his school things___ her.
--- Mum, can I have something ? --- Sorry. There is in the fridge.
—If you have any trouble, be sure to call me. —__________________________.
There was ________ rain in Beijing this summer.
We will have 7 days ______during National Day.