Barron s SAT II 化学

本书特色

《Barron's SAT 2 化学(*新版)(英文版)(出国留学考试用书)》：备考指南，考点透析，数百道习题邀您轮番操练，诊断测试助您认清强弱项，全真测试题帮您考前热身。

内容简介

简介 　　《barron's sat 2 化学(*新版)(英文版)(出国留学考试用书)》：备考指南，考点透析，数百道习题邀您轮番操练，诊断测试助您认清强弱项，全真测试题帮您考前热身。

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插图：A strategy is a goal-directed sequence of mental operations. Selecting a strategy is themost important and also the most difficult step in the problem-solving process.Although there may be several strategies that will lead to the solution of a problem,the skilled problem solver uses the most efficient strategy. The choice of the mostefficient strategy is based on knowledge and experience as well as a careful applica-tion of the clarify and explore steps of the problem-solving method. Some problemsmay require the use of a combination of strategies. The following search methods may help you to select a strategy. They do not rep-resent all of the possible ways in which this can be done. Other methods of strategyselection are related to specific content areas. a. Trial-and-error search: Such a search either doesn't have or doesn't use informa- tion that indicates that one path is more likely to lead to the goal than any other path. Trial-and-error search comes in two forms, blind and systematic. In blind search, the searchers pick paths to explore blindly, without considering whether they have already explored these paths. A preferable method is systematic search, in which the searchers keep track of the paths they have already explored and do not duplicate them. Because this method avoids multiple searches, systematic search is usually twice as efficient as blind search. b. Reduction method: This involves breaking the problem into a sequence of smaller parts by setting up subgoals. Subgoals make problem solving easier becaue they reduce the amount of search required to find the solution. You can set up subgoals by working part way into a problem and then analyz- ing the partial goal to be achieved. In doing this, you can drop the problem restrictions that do not apply to the subgoal. By adding up all the subgoals, you can solve the "abstracted" problem. c. Working backward: When you have t