复发性阿弗他溃疡（）
A.病因不明
B.病毒感染
C.苍白螺旋体感染
D.局部刺激
E.真菌感染
参考答案：A
—How did your father deal with you?
—We were lucky to ____ being punished.
A．admit
B．escape
C．consider
D．stop
局域网常见的拓扑结构有星型、总线型和环型结构。
