A textbook can be a good company that one can keep.It guides you to the ocean of knowledge,to see what things are like,to find the solution to the problem you meet.However,you cannot throw yourself totally depending on it.It is a guider but not a repetition that you follow with.How you use it leads to different result.（纯人工,世间仅此版本,如有雷同,纯属巧合）
