1. My particular experience is largely in oil, and the search for oil has done more to improve deep drilling than any other mining activity.
largely大致，大概的意思，相当于roughly.说到这个词，我们可以联想一下有关词组。at lagre,这个词组应该不陌生，我们在第三册的出逃的美洲狮一颗中学过，a lion at large。
at large 全部的，整个的，总的说来；自由的，逍遥法外的；无固定职业的
与这个词组意思相近的是：on the loose 散漫，放荡
例句：He was a desperate criminal on the loose.
他是个逍遥法外的凶暴的罪犯。
2. The geologist needs to know what rocks the drill has reached, so every so often a sample is obtained with a coring bit.
every so often 偶尔，时常
例句：Every so often we drive down to Devon to visit my wife's parents.
我们偶尔开车去德文看望我岳父母。
3.This pressure must be under control, and we control it by means of the mud which we circulate down the drill pipe.
under control 被控制住
例句：The strike there was securely under the union's control.
那里的罢工处于工会的牢牢控制之下。
He kept the situation under control.
他把情势控制下来。
by means of 通过，用，借助于
例句：He let himself down slowly by means of a tope.
他借助一根绳子慢慢地下来了。
4.We endeavour to avoid the old, romantic idea of a gusher, which wastes oil and gas.
endeavour
n.〈英〉尽力，竭力
例句：What we are undertaking now is an entirely new endeavour.
我们现在干的事业是全新的事业。
v.努力；尽力；竭力
例句：We must always endeavour to improve our work.
我们总要努力改进自己的工作。
