第20题: [单项选择]下列哪个切丝机项修的验收标准不正确() A. 主轴电机刹车片磁极间距离,应不大于0.5mm。 B. 排链经过调整合适后,上排链约下垂15-20mm。 C. 更换垫片时当切削压缩后易于膨开的原料时,用较厚垫片。 D. 主轴电机刹车片磁极要保证周边为等距离。 参考答案:C
第21题: [单项选择]{{I}}Questions 18 - 21 are based on the following dialogue.{{/I}}What are the speakers talking about A. A chemistry assignment. B. A study that their chemistry professor did. C. A class that the woman is taking. D. A possible job. 参考答案:D 答案解析:[听力原文]18-21
M: Hi, Mary. Do you want to start writing a lab report after we finish this experiment