菌群失调症中白色念珠菌是常引起内源性感染的病原菌.（）
参考答案：对
I _____ that actress in quite a few films, but her name escapes me for the moment. [ ]
A. saw
B. have seen
C. see
D. had seen
首先访问结点的左子树，然后访问该结点，最后访问结点的右子树，这种遍历称为 ( )。
A．前序遍历
B．后序遍历
C．中序遍历
D．层次遍历
