如图所示，理想变压器原线圈接入交流电
，副线圈接有一电压表和电阻为R 的负载，电压表的示数为10V．在t=
时（T为交变电流的周期），原线圈两端的电压的瞬时值为
V。由此可知变压器的原副线圈的匝数之比为 （ ）
A．
B．
C．10：1
D．1：10
答案：C
理想变压器原线圈接入交流电
，在t=
时，瞬时值
，则可知原线圈电压的有效值为100V，已知电压表的示数为10V，根据原副线圈两端电压与匝数成正比，即
，故C正确
故选C
完形填空。(15分) Hello, everyone! My name is . I’m a boy. I’m thirteen. I’m in No.4 . I’m in Class One, Grade . I’m from America. My is brown and my mouth is . My English teacher is Li. She is . I think she is 22. Bob and Jane my friends. Bob is Cuba. is tall and black. He has black hair and big . Jane is from England. She is tall and white. She blond hair and a big nose. Bob and Jane are 12 old. They are in Grade One, , but in Class Two.
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