A:a
B:﹣ a
C:aa
D:﹣ aa
俗话说“大树底下好乘凉”“千里之堤,溃于蚁穴”。这都体现了
如图所示,电源电动势为E,内阻为r,当滑动变阻器的滑动端向右移动时,则( )
Why not her to go with you?
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