He began to take political science_____ only when he left school. 

Many people think they have to spend a lot of money to keep healthy. Leading a healthy lifestyle doesn't have to cost much,         . 

I don’t like her face;        , she smokes, which is something I hate.

----- Now that you like the portable personal computer so much, why not buy one? It is of great use to your work. ---- Well, I can’t afford _____ computer at present．

He devoted himself ________ to his research work, having no time to play.