下列方程中是关于x的一元二次方程的是( )
A:3x2-2xy-5y2=0
B:ax2+bx+c=0
C:x2+1x2=0
D:(x-1)( x+2)=1
用适当的介词填空
— When shall we go to watch the basketball match in the sports centre?
— we the work tomorrow.