单项选择题6 Construct a Huffman tree from 4 leaf nodes with weights of 9, 2, 5 and 7, then the weighted path length of the tree is ().
单项选择题劳动保险费是支付离退休职工的退休金、价格补贴、医药费、退职金、6个月以上病假的工资等，它归属于
