secondary unit短语¹⁴⁴⁹⁷²⁺² 基本例句 辅助热交换器 Yet, energy recovery can be achieved easily by utilizing the four- quadrant characteristic of the secondary unit together with high efficiency and good energy saving feature. 利用液压马达的四象限工作特性，能够有效地实现能量的回收与再利用，具有很高的效率和很好的节能效果。 cnki