I didn’t know it could do terrible ______to your heart and lungs or ______was more difficult for smoking couples to become pregnant.

Do you brush ___ every day?

In Shanghai, people______ thousand tons of watermelon every summer.

 ---- When shall we start? ---- You are to gather at the _______ at 8:00 tomorrow morning.

Human life is everywhere a ____ in which much is to be endured and little to be enjoyed..