Chemistry did not emerge as a science until after the scientific revolution in t he seventeenth century and then only rather slowly and laboriously. But chemical knowledge is as old as history, being almost entirely concerned with the practical arts of living. Cooking is essentially a chemical process; so is the melting of metals and the administration of drugs and potions. This basic chemical know ledge, which was applied in most cases as a rule of thumb, was nevertheless dependent on previous experiment. It also served to stimulate a fundamental curiosity about the processes themselves. New information was always being gained as artisans improved techniques to gain better results.The development of a scientific approach to chemistry was, however, hampered by several factors. The most serious problem was the vast range of material available and the consequent difficulty of organizing it into some system. In addition, there were social and intellectual difficulties, chemistry is nothing if not practical; those who practice it must use their hands, they must have a certain practical flair. Yet in many ancient civilizations, practical tasks were primarily the province of a slave population. The thinker or philosopher stood apart from this mundane world, where the practical arts appeared to lack any intellectual content or interest.The final problem for early chemical science was the element of secrecy. Experts in specific trades had developed their own techniques and guarded their knowledge to prevent others from stealing their livelihood. Another factor that contributed to secrecy was the esoteric nature of the knowledge of alchemists, who were trying to transform base metals into gold or were concerned with the hunt for t he elixir that would bestow the blessing of eternal life. In one sense, the second of these was the more serious impediment because the records of the chemical processes that early alchemists had discovered were often written down in symbolic language intelligible to very few or in symbols that were purposely obscure.
36. What is the passage mainly about? A The scientific revolution in the seventeenth centuryB Reasons that chemistry developed slowly as a scienceC The practical aspects of chemistryD Difficulties of organizing knowledge systematically
37. According to the passage, how did knowledge about chemical processes in crease before the seventeenth century?A Philosophers devised theories about chemical properties.B A special symbolic language was developed.C Experience led workers to revise their techniques.D Experts shared their discoveries with the public.
38. The word“hampered" in Line 1 Para 2 is closest in meaning to_____ .
A recognized
B determined
C solved
D hindered
39. The word“it" in Line 3 Para 2 refers to which of the following?
A problem
B material
C difficulty
D system
40. Which of the following statements best explains why“the second of the se was the more serious impediment" （Lines 5-6 Para 3 ）? A Chemical knowledge was limited to a small number of people.B The symbolic language used was very imprecise.C Very few new discoveries were made by alchemists.D The records of the chemical processes were not based on experiments.
