The house could fall down soon if no one ______ some quick repair work

Bob isn’t feeling well He has caught acold —Everybody seems to have ____ because of the changeable climate in spring here

Our maths teacher set so difficult an examinationproblem ______ none of us worked out.

How can they expect to learn anything ________theynever listen

n environment can help the city bid for the Olympics, which ______ will promote its economic development.