A.先將指針回零B.風(fēng)表迎向風(fēng)流C.風(fēng)表與風(fēng)流方向垂直D.待翼輪轉(zhuǎn)動(dòng)正常后,相繼打開(kāi)計(jì)數(shù)器和秒表
A.3.6m2B.1.8m2C.2.5m2D.1.6m2
A.巷道墻高B.巷道凈高C.梯形巷道上底凈寬D.梯形巷道下底凈寬