I have many friends, some of them are businessmen .
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为创造良好的视觉条件,减小因风量过大而造成的煤尘飞扬,风筒距工作面必须保持一定距离。()
What you don’t like him is none of my business .
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掘进机切割机构空载悬臂摆动试验次数为3次,摆动时间误差为±IS。()
半煤岩巷是指掘进断面中,岩层(包括夹石层)占掘进断面大于1/5小于4/5的巷道。()