采煤工作面安全工程质量分为三个等级,即优良品、合格品、不合格品。
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Ⅱ类爆炸性气体按最大试验安全间隙(MESC)或最小点燃电流(MIC)的大小分为三级。()
A. 正确
B. 错误
() blow more or less constantly(except when monsoons prevail)throughout all seasons at a mean speed of around 14 knots and are generally strongest in the late winter.
A. Trade Winds
B. Winds of the temperate zones
C. Monsoons
D. Land and Sea Breeze