Bad habits, _________ formed, are difficult to get rid of.
Most of the inhabitants (居民) can’t afford to buy houses of their own, because the price is rising __________.
__________ most efficient way to understand thousands of new words is to gain __________ good knowledge of basic word formation.
—Can you help me with the math problem, Dad? ___________.—OK, let me think it over.
— Oh, my God,I left my portable computer in the taxi!— ______. Let’s call the taxi company first.
---______ he managed to solve the problem?---Oh,he turned to Professor Lee for advice.