有关数列中项的变换 ,如项的抽出、插入、公共和重组等问题是数列中的典型题型 ,极富思考性和挑战性 ,备受各级各类考试命题者的青睐 ,频频出现在各级各类考试中 ,应引起同学们的高度重视 .下面采撷四例并予以分类导析 ,旨在探索题型规律 ,揭示解题方法 .　　 1.项的抽出例 1　 The transformation of the items in the series, such as item extraction, insertion, public and reorganization, are typical questions in the series. They are highly reflective and challenging and have been favored by all types of examination propositions. All types of examinations at various levels should arouse great attention from the students. The following four cases were collected and classified for guidance. The purpose was to explore the law of the questions and reveal the method of solving the problems.