13-7. The geologist needs to know what rocks the drill has reached, so every so often a sample is obtained with a coring bit.


【译文】地质学家需要知道钻头已到达什么样的岩层,因此时常要用芯钻头取样。


【讲解】the geologist中的the表示类别,指“地质学家这类人”。


【单词和短语】


every so often:时常。


13-8. It cuts a clean cylinder of rock, from which can be seen the strata the drill has been cutting through.


【译文】这种钻头能切割一段光滑的圆柱形岩石,从中能看出所钻透的地层。


【讲解】can be seen the strata…through乃倒装结构,自然语序是the strata…through can be seen。因为主语过长,倒装可以避免头重脚轻。the drill has been cutting through是定语从句,修饰strata。


13-9. Once we get down to the oil, it usually flows to the surface because great pressure, either from gas or water, is pushing it.


【译文】一旦到达油层,石油就会由于来自天然气或水巨大压力而流出地面。


【讲解】once we get down to the oil是时间状语从句,once是连接词。句中的两个it都指oil。either from gas or water乃非限制性定语,修饰pressure。


13-10. This pressure must be under control, and we control it by means of the mud which we circulate down the drill pipe.


【译文】必须对这种压力加以控制,我们用让泥桨顺着钻杆向下循环的方法来控制压力。


【讲解】it指pressure。


【单词和短语】


circulate: 环行;环流;循环(to move around within a system, or to make something do this),

例如:
The earth circulates around the sun. 地球绕着太阳转。


Blood circulates through the body. 血液在体内循环。


13-11. We endeavour to avoid the old, romantic idea of a gusher, which wastes oil and gas.


【译文】我们尽量避免使用陈旧浪漫的、会浪费石油和天然气的喷井方法。


【讲解】of意为“关于”。


13-12. We want it to stay down the hole until we can lead it off in a controlled manner.


【译文】在用能控制的方法把石油引上来之前,我们要让它留在钻孔下面。


【讲解】句中两个it都指oil。to stay down the hole作宾语补足语。