— What should we do to reduce(减少) food waste?
— In a restaurant only order as ________as we need and try to eat it up.
A：much
B：many
C：more
D：most
（Ⅰ）若g（x）=f（x）﹣a为奇函数，求a的值；
（Ⅱ）试判断f（x）在（0，+∞）内的单调性，并用定义证明．
如图所示的下列实验中，有感应电流产生的是（ ）
