两个电阻R1和R2串联在电路中,R1和R2两端的电压之比2∶3,若将它们并联在电路中,电阻R1和R2的功率之比为
A:4∶9
B:2∶3
C:3∶2
D:2∶5
与我国秦岭-淮河一线基本一致的 ( )
The girl usually does her homework _____ it is very late at night.