工革跳汰人工床石的合适粒度是多少?
参考答案:
8~20mm。
You shouldn't have the machines _____all the while; you ought to have them _____now and then.[ ]
A run; repair
B. running; repairing
C. run; repaired
D. running; repaired
王维精通音乐又擅长绘画是()的代表作家。