如图所示是研究电流与电压、电阻的关系的电路图.实验分“保持电阻不变”和“保持电压不变”两步进行,在“保持电阻不变”这一步实验时应( )
A:保持R2滑片的位置不动
B:保持R2两端的电压不变
C:保持R1不变,调节R2的滑片到不同的适当位置
D:保持电路中电流不变
如果x+y=6x-(m-1)y=9中的解x、y相同,则m的值是( )
Wang Lei
How old is he?
1.
Where does he live?
2.
How far is it from his school?
3.
How does he get to school?
4.
Why did the whole school know him?
Because he got the first place in 5.