Lesson 13 The search for oil
by T. F. GASKELL
from The Search for the Earth's Minerals from Discovery
13-1. The deepest holes of all are made for oil, and they go down to as much as 25,000 feet.
【讲解】go down to as much as…等于get as far as…。much相当于deep。they指holes。
13-2. But we do not need to send men down to get the oil out, as we must with other mineral deposits.
【讲解】as we must with other mineral deposits是方式状语从句，must后省略了send men down。with意为“对于”。
13-3. The holes are only borings, less than a foot in diameter.
【讲解】a foot in diameter意为“直径1英尺”。
13-4. My particular experience is largely in oil, and the search for oil has done more to improve deep drilling than any other mining activity.
【讲解】the search for oil作主语。activity后省略了has done。to improve deep drilling作方面状语，修饰has done。
13-5. When it has been decided where we are going to drill, we put up at the surface an oil derrick.
【讲解】where we are going to drill乃真正的主语，it是形式主语。an oil derrick作put up的宾语。
13-6. It has to be tall because it is like a giant block and tackle, and we have to lower into the ground and haul out of the ground great lengths of drill pipe which are rotated by an engine at the top and are fitted with a cutting bit at the bottom.
【讲解】句首的it指an old derrick。great lengths of drill pipe… bottom作lower和haul的宾语。
length是量词，又如：a length of stove pipe（一节烟囱），a length of rope（一节绳子）。
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.
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.