课本中的习题往往具有典型性,能揭示一类数学题的解法。习题做完后,对有些题目若能作进一步的思考,对题目的条件、结论作适当的变形,会引申出一些新的题目,这对提高解题能力是大有帮助的。历年来的中考试题不少就是从课本习题变形和引申出来的。现举一例加以说明。 The exercises in the textbook are often typical and can reveal solutions to a class of math problems. After the exercises are done, if some questions can be further considered, and the conditions and conclusions of the questions are appropriately modified, some new topics will be drawn, which will greatly help in improving the ability to solve problems. Many of the mid-term exam questions over the years have been derived from textbook texts. Here is an example to illustrate.