A:Their parents were killed
B:Being killed
C:Their parents killed
D:Killed
水圈是地球的外部圈层中( )
估计35的值是 ( )
两个定值电阻R1和R2,若R1=R0, R2=nR0 两个电阻可以任意组合分别接在某电压不变的同一电路中,请证明电路最大总功率和电路最小总功率比值为:(n+1)2/n