There is playground in our school. And playground is so big.
A:a; a
B:a; the
C:the; a
D:the; the
⑦铁水 ⑧冰水混合物.其中属于纯净物的有____(均填序号),属于混合物的有____.
我们知道,经过原点的抛物线的解析式可以是y=ax2+bx(a≠0)