When advancing and uncovering coal in roadway, better construction method is vibration shot, metal framework, borehole bleed-off and hydraulic hole, of which vibration shot is principal.
井巷掘进揭煤时，较好的施工方法是震动放炮，金属骨架，钻孔排放和水力冲孔，尤以震动放炮为主。
2
Bleed photos off the edge of the page.
把照片从页面边缘上撕下来。
3
Up to 20 percent of the top airflow should bleedoff down the sidewalls.