He once observed that “All happy families ________ one another, but each unhappy family is unhappy in its own way”.(2012·桂林十八校联考)
We won’t keep winning games _______ we keep playing well.
—What time do we have to be at the gate? —_______ passengers start to board the plane.
Simon thought his computer was broken _______ his little brother pointed out that he had forgotten to turn it on.
Don’t be afraid of asking for help _______ it is needed.
Food shortage will long be a worldwide problem _______ much has been done to supply enough for everyone.