I know you are shorter than your two brothers, but you run _______ of you three.

---How many elephants are there in the zoo?--- There aren’t _______.

—Have you ___________ been to Beijing? —Yes. But only once.

— Kitty, there’s ________ cooking oil left in the kitchen. Would you please go to the supermarket and get ________?— OK, Mum. 

- How often do you visit your grandparents, Tom ?   --__________