—Tina didn't go to school yesterday, did she?
— . Bcause she was badly ill.
A:Yes, she did
B:Yes, she didn't
C:No, she didn't
D:No, she did
已知磁敏电阻在无磁场时电阻很小,有磁场时电阻变大,并且磁场越强阻值越大。为探测磁场的有无,利用磁敏电阻作为传感器设计了如图所示电路。若探测装置从无磁场区进入强磁场区,电源的电动势E和内阻r不变,理想电压表、电流表的示数将发生变化,电压表V1、V2示数变化量的绝对值分别为∆U1、∆U2,已知电阻R大于电源内阻r,则( )
造成下图岩石层层剥离、不断破碎的地质作用主要是( )