绿色开花植物的一生是从种子开始的(更确地说是从受精卵开始的),所以先讲种子。让学生学习“种子”的目的是要使他们了解:为什么一粒种子在适宜的条件下能够萌发成为幼苗?这是教材的中心。显然,种子之所以能够萌发成为幼苗是由内外两方面原因决定的。从 The life of a green flowering plant begins with the seed (and more specifically from the fertilized egg), so talk about the seed first. The purpose of getting students to learn “Seed” is to make them understand: Why a seed germinate under the proper conditions and become a seedling? This is the center of the textbook. Obviously, the reason why seeds can germinate into seedlings is determined by both internal and external causes. From