Edison was a clever boy, and ______ he was fourteen, he had learned advance mathematics by himself.
We should take ______of this opportunity to make a good impression on them.
What is the ______ to Beijing and back?
He didn’t makeclear when and where the meeting will be held.
I can’t quite remember ________ you started playing golf.
----Did you go to the cinema last night? ----No, We, but our car broke down on the way.