A. 对流管、水冷壁 B. 集箱、过热器 C. 燃烧设备、炉墙
A. RS-485 B. 8251串 C. RS-232 D. RS-422
A. What is this customers address? B. Does this customer have any unpaid bills? C. What is the balance in this customers account? D. What are the total sales for each of the last 6 months?