Plants and trees need water to grow; ______, friendship needs our heart and passion to develop.

s going to the concert with you this weekend,but I can’t now．– ______．

rovinces have been hit with smog. If _______ unsolved, the problem may lead to more serious results.

172. Since the disaster of September 11, American economy has got into a jam. The underlined part probably means _____.

orts to raise money for his program were ______ because, no one showed anyintention to take a cent out of their pockets.