-_____ was your trip?
-It was very nice.[ ]
A. What
B. Where
C. How
D. When
答案:C
抛物线y=2x2+4x与x轴的交点坐标分别是A(______),B(______).
高炉开炉前配管工应检查的有()系统。
A.上料系统
B.风、渣口有无漏水
C.高炉各冷却设备