— did you stay in the library?
— I stayed there for over two hours.
A:How long
B:How often
C:How many
学习宋元历史后,某班同学作了如下主题演讲,你认为能准确概括这段历史的基本特征的是( )
如图甲所示的电路,小灯泡L标有“6V 3W”字样,小灯泡的I﹣U关系如图乙所示,R为10Ω的定值电阻.当小灯泡电功率为0.8W时,定值电阻R消耗的功率是 ____W,电流表的示数为 ____ A.
已知α,β是锐角,sinα=x,cosβ=y,cos(α+β)=﹣35,则y与x的函数关系式为( )