题目

完形填空In our life, we meet quite a lot of people: some just pass by while others can 1.________ our lives. Miss Bella is such a person. She taught me two years only. 2.________， she has taught me a lot in many ways.Every day she began her classes with a smile and a fresh face. She made me realize that warm 3.________ could change a person. I was shy but I wasn't 4.________ in her classes at all. She gave lessons in a 5.________ way from other teachers. We had many 6.________ to talk about problems in English classes. Miss Bella would thumb up (竖起大拇指) to encourage us 7._______图甲是一个单摆振动的情形，O是它的平衡位置，B、C是摆球所能到达的最远位置．设摆球向右方向运动为正方向．图乙是这个单摆的振动图象．根据图象回答：（1）单摆振动的频率是多大？（2）开始时刻摆球在何位置？（3）若当地的重力加速度为10m/s2，试求这个摆的摆长是多少？