A venetian vent or rice ventilator is used in stowage of which cargo?（）. ["Bagged cargo","Bulk grain","Bulk rice","Refrigerated good"]
如何保证电能质量的频率指标？
填写工作票时，（）出现错、漏、多字情况时，该工作票予以作废，在“备注栏”注明原因，并重新办理工作票。 ["断路器、隔离开关、接地开关等设备的名称和编号","断开、合上、拉开、投入、退出、停用、取下、给上、装设、拆除等操作动词","继电保护连接片的名称和编号","工作许可时间、工作终结时间","接地线安装位置及编号"]
A drop in compression pressure in one cylinder of a diesel engine can be caused by（） ["a leaking fuel injection nozzle","a clogged air filter","early fuel injection","burned valve"]
A grapnel is a（）. ["device for securing a chain topping lift","hook to prevent the anchor cable from slipping","device used to drag for a submerged cable or line","type of clam bucket used for discharging bulk cargo"]
开关站的电气主接线方式有哪几种？其优缺点及适用范围分别是什么？
