若a-b+c=0，则关于x的一元二次方程ax2+bx+c=0（a≠0）有一根是[ ]
A.x=1
B.x=-1
C.x=0
D.无法判断
答案：B
I have advised him not to do like that, but he still insists on doing it that way. I think he has his own opinion .
A．in all
B．above all
C．after all
D．first of all
以下关于旅游行业组织的正确描述是（）。
A、官方组织
B、自愿加入
C、不营利
D、对会员有约束力
think he has his own opinion .