下列关于Huffman树和Huffman编码的说法正确的有: Which sentences of the followings are right about Huffman tree and Huffman code:

A.Huffman树一定是满二叉树。A Huffman tree must be a full binary tree.#B.Huffman编码是一种前缀编码。Huffman code is a kind of prefix code.#C.Huffman树一定是完全二叉树。A Huffman tree must be a complete binary tree.#D.Huffman编码中所有编码都是等长的。All codes in a Huffman code have the same length.#E.对于同样的一组权值两两不同的内容可以得到不同的Huffman编码方案。Different content with the same group of weights can get different Huffman codes.#F.使用频率越高的字母，Huffman编码越长。The higher