We can't _____ one to change the habits of a lifetime in a short time.

He had his camera ready just         he saw something that would make a good picture．

—Mum,it is nice weather.I want to skate this afternoon.—Don’t you think the ice on the lake is too thin to __________ your weight?

－ I came all the way to inform you of the time and place of the meeting.－You could have __________ yourself the trouble by calling me. 

My parents _____ in Hong Kong. They were born there and have never lived anywhere else.