如果关于x的方程mx2+(m-2)x+5=0是一元二次方程,那么m______.
因为关于x的方程mx2+(m-2)x+5=0是一元二次方程,所以二次项系数m≠0.
Entering the room,I found Mary_____at the desk and_____a letter.
A.seated wrote
B.sitting written
C.seating writing
D.seated writing
如图所示,合上开关后,发现铁钉旁边的小磁针静止时S极指向铁钉A端,则A 端是______ 极,电源D端是______ 极.