牙周膜纤维的恢复最慢的位置是（）
A.主纤维
B.崤上纤维
C.根中部纤维
D.根尖区纤维
E.颈部主纤维
参考答案：E
Look and write. （看图. 填上适当的单词把句子补充完整，每空一词）
1. — How much are the ________? — They're ________ yuan.
2. — What's the weather like ________ Beijing? — It's________.
3. I'd ________ 3 ________.
4. How many ________ ________ there?
5. It's ________. It's ________ to go to bed.
下面哪个命令可以查看RIPng数据库信息（）
A.show ipv6 protocols
B.show ipv6 interface
C.show ipv6 rip catabase
