公司生产的低碳钢冷轧钢带一部分用于冲压。
参考答案：对
-He __________ his mother do the housework at the age of eight.
-We should help our parents with the housework. I did it when I __________ six.
A. helped, was
B. helps, was
C. helped, am
D helped, am
集中式空调系统划分的原则是什么？
