---The boy is very clever.
---He can work out the math problem ________.
--Where is David?
--I think he ________ Australia.
---What's_______ favourite colour?
---_________favourite colour is green.
---What's wrong ________ your clock?
---It's doesn't work.
---Hello! May I speak to John?
---Yes, ________.
--Can you answer the telephone? I'm busy ________ the Internet.
--OK. I'll get it.