下列牙中只出现单根管的牙是
A. 上颌中切牙
B. 下颌尖牙
C. 上颌第一前磨牙
D. 下颌中切牙
E. 下颌第二前磨牙
The plae has developed from a fishing port into a tourist center.
Families play an important role in forming children's character.
This exercise is aimed at improving health rahter than losing weightl