如图电路中,电源电压为6V,电流表A2的读数为0.3A,电流表A1的读数为0.8A,求R1、R2的电阻值.
解:∵两电阻并联
∴I2=I﹣I1=0.8A﹣0.3A=0.5A,
,
By now, more than 100 photos ________ back to the earth by Chang’e-3.
A.had been sent
B.has been sent
C.have been sent
D.will be sent
兔瘡主要发生于()
A.1月龄以内兔
B.2月龄兔
C.3月龄兔
D.4月龄兔
E.5月龄兔