应有基低位发热量为（）的煤叫标准煤。
参考答案：7000×4.18kj/kg（或7000大卡）（或29307.6KJ）
How did the girl _______ the fire and helped Mr. Sun out?[ ]
A. put on
B. put off
C. put out
D. put up
如何判断凝汽器冷却水管积垢、堵塞？
