—The research on the new flu virus vaccine is challenging and demanding. Who do you think can do the job?     —_______ my students have a try?

Sometimes most of us probably are angry______our friends, parents or teachers. 

How ________ I help them to understand when they don’t listen?

- Mr Jackson, __ we go rock climbing? m Yes, but you must use ropes.

You'd better not ride the bicycle on snowy days; you ______ fall．