有这样的一种试题,即给出某一定量,然后根据此定量推断多种有机物。这种类型题是近几年高考或竞赛的热点。不少同学遇到这类试题时,摸不到窍门,发散不开,而采用穷举法求解,往往事倍功半。若用“等量代换”法则方便得多,现举数例证明之。 There is a kind of test that gives a certain amount of quantification, and then infers a variety of organic substances based on this quantification. This type of question is a hot spot for the college entrance examination or competition in recent years. Many students encountered such questions, they couldn’t reach the door, and the divergence could not be opened. However, using the brute-force method to solve them often resulted in less work. If you use the “equal substitution” rule is much more convenient, the present example demonstrates.