The marine diesel engine is a type of diesel engine used on ships The （） of its operation is not very difficult to understand. ["principle","principal","cause","case"]
茶道是（）的艺术。 ["综合性","生活中","偶然性","由无至无"]
弧后扩张的模式有哪些？
招商银行可受理（）币种的信用卡柜台缴款业务。 ["人民币","美元","港币","欧元"]
请问焦炉炉前焦库有何作用？
请问决定最高开工率的要素有哪些？
