下列计算正确的是( )
A:3a﹣2a=1
B:x2y﹣2xy2=﹣xy2
C:3a2+5a2=8a4
D:3ax﹣2xa=ax
如图所示的电路中,当灯泡L1烧坏时(设电源电压U不变),则通过 L2的电流( )
In summer we like staying in the room w____ window faces north.