Smoking is bad ___ your health.
—__________ T-shirt do you like better, the red one or the blue one?—I prefer the red one.
Your English teacher has never lost his temper, ___________ he?
You had better ____________ because you have to drive back home.
As we all know, it’s not polite to keep others _________ for a long time.
An official ___________ by some reporters on food problems in Shanghai yesterday.