A:when you bought this MP5
B:how long you have had this MP5
C:how soon you will buy a new MP5
D:where you bought this MP5
AB和BC是由同种材料制成的长度相同、横截面积同的两段导体,将它们串联后连入电路中.比较通过它们的电流的大小,有()
化简3(2x+1)-2(x-1)结果正确的是( )