2. 考研
  3. 【F1】Petroleum is the largest source of liquid fuel, and, in spite of attempts to develop synthetic fuels, and the continued use

【F1】Petroleum is the largest source of liquid fuel, and, in spite of attempts to develop synthetic fuels, and the continued use

admin2017-10-23  32
问题     【F1】Petroleum is the largest source of liquid fuel, and, in spite of attempts to develop synthetic fuels, and the continued use of solid fuels, world consumption of petroleum products is about four times greater now than in 1940.
    Crude petroleum oil from different oilfields is never exactly identical in composition. Although all petroleum is composed essentially of a number of hydrocarbons, they are present in varying proportions in each deposit, and the properties of each deposit have to be evaluated.【F2】Samples are subjected to a series of tests in the laboratory, the object of which is largely to determine the correct processing methods to be adopted in each case.
    Petroleum is not normally used today in the crude state.【F3】The mixture of oils of which it is composed must be separated out into a number of products such as petrol, aviation spirit, kerosene, diesel oils and lubricants, all of which have special purpose. The main method of separation used, in refineries is fractional distillation, although further processing is normally required to produce marketable petroleum products. The different hydrocarbons present in petroleum have different boiling temperatures, and the fractions can therefore be isolated according to their boiling temperatures. Petrol, for instance, is a mixture of the lower-boiling hydrocarbons, with boiling temperatures ranging from 100℃ to 400℃. Diesel oils on the other hand have boiling temperatures of upwards of 400℃.
    【F4】Distillation was originally carried out in batch—stills and, although this is still done for special purposes, the development of the pipe—still has revolutionized refinery processes, since it allows continuous vaporization and rectification of the fractions. The pipe-still consists of a bricok-lined furnace, in which is fitted a battery of tubes, through which the crude oil is pumped. The oil is heated, and petrol vaporization occurs. The oil then enters the fractionating tower, where it is distilled by coming into contact with condensed vapor which has previously been evolved from the still. Fractions of different boiling ranges are drawn off at different points in the tower, or, in some plants, in a series of towers, each one distilling successively heavier fractions.
    【F5】The heavier distillates, such as gas oil, undergo various other processes, of which the most important is known as cracking. In this process, they are heated to a temperature of about 550℃, as a result of which the heavier molecules are broken up, lighter oils such as petrol being produced. Catalytic cracking, in which silicon compounds are used as catalysts to aid the process of decomposition, gives higher octane petrols. These are widely used as motorcar fuels, since the high octane value reduces the tendency of the fuel to detonation.
【F2】
选项
答案油样被送进化验室进行一系列化验，其目的在很大程度上决定了每一个样品应采取的正确提取方法。
解析 这是一个含有非限定性定语从句的主从复合句。主句中的谓语动词be subjected to暗含被动，在翻译为汉语时可以不转化为主动形式，沿用句子的形式。非限定性定语从句中的先行词the object所指“油样被送进化验室进行化验的目标”。而其后的被动语态结构to be adopted…无法猜测这一动作的施动者，因此应采取主动的翻译方法。sample“标本，样品，采样，抽取……的样品”。
转载请注明原文地址:https://jikaoti.com/ti/sok7FFFM
0

考研英语一

相关试题推荐
随机试题
最新回复(0)