简述直接数字控制（DDC）系统的工作原理。
The purging of air from an elector-hydraulic steering gear unit is necessary when（） ["changing over to hand pump operation","engaging the trick wheel","the system has been filled with new oil","the rudder angle indicator does not match the helm positio"]
下列不能作为公司发起人出资财产的是哪些？（） ["土地使用权","商标权","专利权","特许经营权"]
客户经理不能重复建立同一个潜在客户信息。
The safe working load for the assembled cargo gear and the minimum angle to the horizontal for which the gear is designed shall be marked on the（）. ["deck","head of the boom","heel of the boom","mast or king post"]
监管油品时需要注意的问题有哪些？
