課后練習：

1. Petroleum refining is the_____ of petroleum into fractions and the subsequent treating of these fractions to make them into petroleum products.

A operation B introduction C separation D separable

2. Most petroleum products, including kerosenes, fuel oils, lubricating oils, and waxes, are fractions of petroleum that _____to remove undesirable components.

A has been treated B have been treated

C be treated D treated

3. Other products, for example, gasolines, aromatic solvents, and even some asphalts, are totally or partly synthetic _____ they have compositions that are impossible to achieve by direct separation of these materials from crude petroleum.

A which B by which C in that D of that

4. Refining petroleum is a complex series of steps _____ the original crude material is eventually converted into _____ products with the desired qualities and perhaps more important, in the amounts dictated by the market.

A for which, sold B by which, sale

C by which, salable D which, sell

5. In fact, a refinery is essentially a group of manufacturing plants that _____ in number with the ______ of products produced.

A vary, various B variety, vary

C invariable, variable D vary, variety

6. If the ______ cannot be sold as, say, heavy fuel oil, they accumulate until refinery storage facilities are full.

A late B latter C lab D light

7. To prevent the occurrence of such a situation, the refinery must be flexible and able to change operations _____.

A what needs B which needs C as needed D that need to

8. In the early stages of refinery development, _____ illuminating and lubricating oils were the main products, distillation was the major and often only refinery process.

A if B unless C until D when

9. As the demand for gasoline increased, conversion processes were developed because distillation could no longer supply the necessary _______.

A quality B quantities C quarter D equator

10. Distillation has remained a major refinery process and a process _____ just about every crude that enters the refinery is subjected.

A to which B for which C by which D of what

11. Thus it is possible to obtain products ranging from gaseous materials _____ the top of the distillation column to a heavy residue or "bottom", which is usually nonvolatile, with correspondingly lighter materials taken off at intermediate points.

A take on B taken off C taken to D took off

12. Indeed, atmospheric distillation may be ____ with a lower boiling fraction ("cut") if it is thought that vacuum or steam distillation will yield a better quality product.

A terminal B term C terminated D turned

答案： 1C 2B 3C 4C 5D 6B 7C 8D 9B 10A 11 B 12 C