下列物质属于纯净物的是( )
A:茶饮料
B:矿泉水
C:纯牛奶
D:蒸馏水
已知(x﹣1)(x+2)=ax2+bx+c,则代数式4a﹣2b+c的值为____
—Yes, ______ I'll call them at once.
That's ____ late! ( )