青少年牙周炎的好发牙位为
A．第二磨牙
B．前磨牙
C．尖牙
D．第一磨牙和切牙
E．所有后牙
参考答案：D
After decades of effort, the city is still trying to _____ how to ban smoking in public places.
A．look through
B．get through
C．figure out
D．take out
右心衰最早出现的特异性体征是（）
A.发绀
B.肝大
C.水肿
D.颈静脉怒张
E.颈静脉怒张和肝颈静脉回流征阳性
