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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Mrs. Brown had a small garden behind her house, and in the spring she planted some vegetables in it. She looked after them very carefully, and when summer came they looked very nice. One evening Mrs. ...
A.
Right.
B.
Wrong.
C.
Doesn’t say.
【多选题】如图所示，是某次抢险救灾现场的一台柴油发电机一端接的变压器。两个线圈的匝数比n1:n2=1：2。a、b两端接Uab=110sin 100πtV的交流电；c、d两端接负载，电阻为R。下列说法正确的是 [ ]
A.
c、d两端电压的有效值是220 V
B.
通过电阻R的电流频率是50 Hz
C.
减小电阻R的阻值，a、b两端的输入电流将变小
D.
减小电阻R的阻值，a、b两端的输入电流将增大