A:no difficulties to find
B:some difficulties in finding
C:no difficulty to find
D:no difficulty in finding
小红向税务部门举报某商场购物不开发票,你认为她的行为属于( )
理想变压器原、副线圈匝数之比为2:1,原线圈接入如图乙所示的正弦式交流电压,副线圈接一个R=55Ω的负载电阻,电流表、电压表均为理想电表,则下述结论正确的是( )