题目

小杨家新装了电辅式太阳能热水器，如图是内部水箱的结构示意图．R的阻值为30Ω．Sl是自动温控开关：水温低于20℃时闭合，电阻R开始加热；当水温高于60℃时自动断开．A、B是水箱中两个相同的实心圆柱体，体积均为500cm3 ， 重力均为9牛，悬挂在水箱顶部的压力传感开关S2上．当水面下降后S2受到竖直向下的拉力达到16N时闭合，电动水泵M开始向水箱注水；当水面上升后拉力小于等于10N时，S2断开，电动水泵M停止注水．请计算：（细绳的质量和体积、 短文填空 It was seven o’clock in the morning, but Jim didn’t g　　1　　 up．His mother came into his room, and w　　2　　 him up．“What’s w　　3　　 with you，Jim？” said his mother．Jim t　　4　　 his mother he had a headache．His mother a　　5　　 him not to go to school, and to s　　6　　 a doctor．At the doctor’s, the doctor looked him over c　　7　　．He said to Jim，“You have got a bad c　　8　　, but it’s nothing serious．” He g　　9　　 Jim some pills(药片)and told him to go home and have a good r　　10　　．At home, after he took some medicine, Jim went to bed．