Based on the operational principle of on/offslip of continuous-circulation system, the forced state of drill pipe was clarified.
从钻井连续循环系统上卸扣卡瓦的工作机理入手，弄清了钻杆工作时的受力状态。
2
Italian Enzo Maresca and Ernesto Chevanton were on target to help Sevilla move two points off the lead, while Espanyol slip to eighth after their first defeat of the season.