What was he doing ______ his father _______ back?A. while; came B. when; came C. when; was coming
—When did the old man die?—He ________a rainy winter evening.
—Could you tell me ?—Certainly.
—Doctor, it seems you like to work with animals.—Yes, I think animals should as our friends.
The 2nd Youth Olympic Games was on TV. So everyone could watch it at home.
They were _________ busy _________ with each other _________ the time.