如果1托等于1毫米汞柱，那么1毫托一定等于1微米汞柱，对吧？

If one torr equals 1 millimeter of mercury, then 1 millitorr must be equivalent to 1 micrometer of mercury, right?

在离海面几千英尺高度上(在拔海高度数千英尺以下)气压递减率大约是每900到1000英尺高度下降1英寸汞柱左右。

For the first few thousand feet above sea level the rate of pressure decrease is in the neighbourhood of 1 inch of pressure for each 900 to 1000 ft.