A:a∥α,b∥α
B:a∥α,b∥β,α∥β
C:α⊥β,a⊥α,b∥β
D:a⊥α,b⊥β,α∥β
抛物线y=x2-2x+1的顶点坐标是( )
Today is really a day. I lost all my money. ( )