— Do you know if we will go for a picnic this Saturday?
— I think we will if we ________ any classes.
A:won't have
B:didn't have
C:don't have
D:aren't having
如图,△ABC是边长为4的等边三角形,△ABD是等腰直角三角形,AD⊥BD,平面ABC⊥平面ABD,且EC⊥平面ABC,EC=2.
(1)证明:DE∥平面ABC;
(2)证明:AD⊥BE.
某种型号的电视机经过连续两次降价,每台售价由原来的1500元,降到了980元,设平均每次降价的百分率为x,则下列方程中正确的是( )
— ,it's not safe enough.
坐标平面上,某个一次函数的图形通过(5,0)、(10,﹣10)两点,判断此函数的图形会通过下列哪一点?( )