【单选题】For binary tree, there are three kinds of traversal modes, and the main difference between these traversal modes is the priority to visit root. Which is the postorder traversal mode? ( )
【简答题】There are many kinds of ants in America. One kind is very strong. People are afraid of it. These ants move in a large group. They eat all the animals on their way. They can kill and eat elephants, and...