数据库管理系统大致分为()部分。
A.6
B.7
C.8
D.5
参考答案:A
Following the girl, we went into a hall, on ____ walls hung a few pictures of some famous scientists.
A.its
B.which
C.whose
D.those
牙石对牙周组织的危害最主要的是
A.机械刺激B.增加了牙面的光滑度C.牙石表面菌斑的致病性D.不利于刮治器的进入E.妨碍洁治