avlB.AttachSubtree(1,(AVLTree)this[0][1]);
avlB.AttachSubtree(2,(AVLTree)this[1]);
this.key=this[0].Key;
this[0]=this[0][0];
this[1]=avlB;
//调整两个节点的高度
((AVLTree)this.Right).AdjustHeight();
this.AdjustHeight();
}
protected void LRRotation()
{
if( this.IsEmpty() )
throw new Exception("My:invalid operation!");
((AVLTree)this.Left).RRRotation();
this.LLRotation();