The machine is cleaned regularly to stop dirt adhering to the working parts.机器要定期清洗以防止灰尘粘附在运转部件上。That year's model had been cunningly designed so that you couldn't see the working parts.那年那款型号的产品设计非常巧妙，完全看不到工作部件。Protein molecules compose all the complex working parts of living cells.活细胞中所有复杂的运行成分都由蛋白质分子构成。