下列关于堆的说法正确的有: Which sentences of the followings are right:

A、堆一定是满二叉树。A heap must be a full binary tree.

B、最小堆中，最下面一层最靠右的结点一定是权值最大的结点。In a minimum heap, the rightest node on the nethermost layer must be the node with the largest value.

C、堆是实现优先队列的惟一方法。A heap is the only method to implement a priority queue.

D、堆一定是完全二叉树。A heap must be a complete binary tree.

E、最小堆中，某个结点左子树中最大的结点可能比右子树中最小的结点小。In a minimum heap, the largest value on some node's left child tree could be possibly smaller than the smallest value of its right child tree.

F、使用筛选法建堆要比将元素一个一个插入堆来建堆效率高。Screening method has a higher efficiency than inserting elements one by one while constructing a heap.