原料预热炉点火时，容易使火嘴点不着火的原因是（）。
A．燃料气压力偏低
B．火嘴阀开度偏大
C．看火孔没关
D．烟道挡板开度过大
参考答案：D
—Are you having much trouble with the course?
— . The only thing I haven't understood so far is the reading we had last night.[ ]
A. Of course
B. Not likely
C. Not really
D. Not a little
欧洲中世纪城市手工业行会、商人公会组织秘书性工作的承担者主要是( )
A．管家
B．帐房先生
C．会长
D．专职秘书性人员
