541. 活塞式压缩机 Piston Compressor
542. 活塞式压缩机基础设计 Basic Design of Piston Compressor
543. 活塞压缩机结构强度 Structural Intensity of Piston Compressor
544. 活赛压机气流脉动 Gas Pulsation of Piston Pressor
545. 货币银行学 Currency Banking
546. 基本电路理论 Basis Theory of Circuit
547. 基础写作 Fundamental Course of Composition
548. 机床电路 Machine Tool Circuit
549. 机床电器 Machine Tool Electric Appliance
550. 机床电气控制 Electrical Control of Machinery Tools
