在配置帧中继子接口时,可配的子接口类型有哪些()
A、point-to-point
B、NBMA
C、point-to-multipoint
D、broadcast
参考答案:A, C
可造成牙髓坏死的原因有()
A.深龋
B.畸形,中央尖折断
C.氟牙症
D.外伤
E.烟斑染色
He suddenly ___ in front of my eyes. [ ]
A. turn down
B. turn up
C. turn on
D. turn off