历史上有乐谱的第一部歌剧出现在哪一年？
What is NOT a function of the steam drum of a marine water-tube boiler（）. ["Receives saturated steam from the generating tubes","Serves as a reservoir of boiler feed water","Holds internal fittings for separation of moisture from steam","Collects steam exhausted from the turbine"]
下列对进程的描述正确的是（）。 ["进程是程序的组成部分","进程是静态的","进程能创建其他进程","用户进程的优先级最高"]
To find the cause of a gasoline engine’s failure to start，you should（）. ["Break the joint in the fuel line at the engine and let the gas run in the bilges","Disconnect the wires at the spark plugs and make the spark jump the gap","Prime the engine with ether through spark plug openings","Ventilate the space，then check the battery，spark plugs，carburetor，and fuel line"]
简述清纱器的形式和工作原理，对比两种电子清纱器的主要工作性能。
络筒工序的工艺参数有哪些？确定各工艺参数的依据是什么？
