The conventional demagnetizing method is not good at inner demagnetization using direct or alternating magnetic field.
常规的交，直流消磁方法对材料内部消磁效果欠佳。

Variable B has a direct effect on variable D, an indirect effect on variable C, and no causal effect at all on variable A.
变量B对变量D有直接的影响，对变量C的影响是间接的，对于变量A则完全没有因果关系上的联系。

As the only direct steamer which call at our port once a month have just departed, the goods can only be shipped next month.
由于唯一停靠我港的月班直轮刚刚驶离，货物只能下月装船。

They are intended for use in electrical equipment operating on alternating current at a frequency not greater than 100Hz or direct current.
他们是用来制造频率不高于100赫兹交流电的手术设备。