畸形中央尖常发生于
A．尖牙
B．下颌双尖牙
C．下颌磨牙
D．上颌磨牙
E．上颌双尖牙
参考答案：B
________ is known to us a11 is that the Diaoyu islands have been part of our Chinese territory since ancient times.
A．As
B．Which
C．It
D．What
属于鼻咽癌临床表现的是（）
A.鼻塞
B.涕中带血
C.听力下降
D.颈淋巴结肿大
E.头痛
