A:①②③④
B:①②③
C:①②
D:①
____个十和____个一,一共有____个豆包.
图示电路中,电源电压不变,R1为定值电阻,R2为滑动变阻器.闭合开关S,移动滑片P,多次记录电压表示数U和对应的电流表示数I,则绘出的U﹣I关系图象正确的是( )
In the bookshop, a reader asked the shopkeeper __________ Who Moved My Cheese was an interesting book.