题目

A geography teacher hung a map of the world’s river distribution(分布) in front of the blackboard. He  41  , “My dear classmates, what   42  does the world’s river distribution have?” “All of them are not straight lines, but bent curved(弯的) lines,” his students replied together. The teacher  43  to ask, “Why are these rivers not in the shape of straight lines but so many curves?” The students began to   44  the question and expressed their different ideas. Some said that the bends(弯道) of rivers   45  the flowing length. When the flood came in sum三年级有男生120人，每人搬2把椅子，一共要搬椅子A．240把B．140把C．220把