Outline It is a long and scientific described article,not story.So it may be a little difficult for us to grasp the main idea of the text.In order to have a clear picture of the whole article,we'd better divide the whole text into several parts. Part One:pl~p2 Part Two:p3≈pl0 Part Three:pl1~the endOutline It is a long and scientific described article, not story. So it may be a little difficult for us to grasp the main idea of the text. In order to have a clear picture of the whole article, we’d better divide the whole text into several parts. Part One: p1~p2 Part Two: p3~p10 Part Three: p11~ the end