（6分）一列简谐横波沿x轴正方向传播，t= 0时刻的波形图象如图甲所示，波此时恰好传播到M点。图乙是质点N（x=3m）的振动图象，则Q点（x=10m）开始振动时，振动方向为 ，从t=0开始，经过 s，Q点第一次到达波峰。
y轴负方向 8s
题目分析：根据t=0时刻的波形图象可知，M点刚开始振动时，沿y轴负方向振动，则波源的起振方向沿y轴负方向，因此Q点开始振动时，振动方向沿y轴负方向；由甲图可知，波长
，由图乙可知，周期
，则波速
，波由M点传播到Q点所用时间
，Q点开始振动到第一次到达波峰的时间
，因此，从t=0开始，经过8s，Q点第一次到达波峰。
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| There was a woman in Detroit ,who had two sons. She was worried about them, especially the younger one, Ben, because he was not doing well in school. Boys in his class made jokes about him because he seemed so __1_ . The mother _2_ that she herself would have to get her sons to do better in school. She told them to go to the Detroit Public Library to read a book a week and do a book report for her. One day, in Ben's _3 , the teacher held up a rock and asked if anyone knew it. Ben put up his hand and the teacher let him _4_ . "Why did Ben put up his hand?" His classmates wondered. "He _5_ said anything. What could he possibly want to say? Well, Ben not only _6 the rock, but also said a lot about it. He named other rocks in its group and even knew _7 the teacher had found it. The teacher and the students were _8_ . Ben had learned all this from doing one of his book _9_ . Ben later went on to the _10 of his class. When he finished high school, he went to Yale University and at last became one of the best doctors in the United States.
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