题目

小明同学家里的电热饮水机有加热和保温两种功能，可由机内温控开关S0进行自动控制。小明从说明书上收集到如下表中的部分数据和图19所示的电路原理图。 额定电压220V 频率50Hz 额定加热功率920W 请解答如下问题：（计算结果若不能整除，保留一位小数） （1）这个电热饮水机正常工作时，在加热状态下的总电流大约是多大？ （2）若电阻R2的阻值为1210Ω，则电阻R1的阻值为多少？ （3）在傍晚用电高峰期，供电电压可能会下降。当实际电压只有198V用所给词的适当形式填空 (10) 1.---Where did you______ (study) last night? ---No, I__________(help)my mother_______(clean) the room. 2.Mike goes to see his grandparents _________(one) a week. 3.To keep healthy，I decide _______ (exercise) half an hour every day 4.He is         (funny) than the other students in his class. 5.The boy enjoys         (swim) very much. 6.His mother often makes him        (clean) his room on weekends. 7.It’s necessary for us         (learn) English well. 8.I’m           (good) at physics than my sister. 9.Dumpling House is          (cheap) restaurant in the city. 10.I think Xi Yangyang is as         (famous) as Mikey Mouse.