— Did the little boy manage _____ the suitcase upstairs? ( )
— No, he didn't.he isn't strong enough even ______ it.
A:to carry, moving
B:carrying, to move
C:to carry, to move
D:carrying, moving
下列函数中是奇函数的是( )
如图所示的光控电路用发光二极管LED模拟路灯,RG为光敏电阻.A为斯密特触发器输入端,在天黑时路灯(发光二极管)会点亮.下列说法正确的是 ( )