A:法国
B:美国
C:德国
D:日本
Nobody will help you __________ you help yourself.
This is _________ elephant. _________ elephant is from Africa.
如图所示为定值电阻R1和R2中的I—U关系图.若将R1和R2并联后接在电压为6V的电源两端,则通过R1和R2的电流之比为____,R1和R2两端的电压之比为____,R1和R2消耗的功率之比为____.若将R1和R2串联在电压为6V的电路中,则R1和R2两电阻消耗的功率之比为____.