A:how to deal with
B:what to deal with
C:how to be dealt with
D:what to be dealt with
如图所示,电源电压不变,R1=4Ω,R2=6Ω,R3=5Ω.当开关S闭合后,电流表示数为0.3A,则电源电压为____ V,电阻R1的功率为____ W.
如图是细胞核的结构模式图,下列关于各结构及功能的叙述正确的是( )
下列哪个不是地图的基本要素( )