---Look! It must be Jack on the playground.---It _____ be him. Because I saw him enter the school library just now.
Mr Yao impressed the students his creative ideas and humorous words.
It is time ____ to school.
—How old ____Li Ping and Lucy ? — Sixteen _____old.
—____ boys are there in your class ? —_____ 22 boys.
—How do you spell “pen”? —___________.