A:/, /
B:/, a
C:the, a
D:/,/
如下图所示,V1和V2是完全相同的两个电压表,都有3V和15V两个量程,闭合开关后,发现两个电压表偏转的角度相同,则R1和R2两端的电压比为
If you want to take several days off, you should ask ____ (permit).
关于世界各大洲分界线的叙述,正确的是( )