-- Look at the boy running on the ground. Is it David?-- It _______ be him. I saw him go to the teacher’s office just now.
Life is always filled ____ sadness and happiness.
— Would you like tea or water? — _________ is OK. I really don't mind.
Alice in Wonderland is a fantastic movie. It's about _________.
China is developing _________ of all the countries in the world.
A moment, please. I'm checking if Mrs. Brown _________ free tomorrow.