B树的表示及基本操作的实现。 1．掌握B树的存贮结构。 2．实现B树中关键字值的插入及删除操作。 3．练习屏幕图形化的显示。 -Representation of the B-tree and the realization of the basic operations. 1. The master of the B-tree storage structure. 2. Keyword value in the B-tree insert and delete operatio