单项选择题
A.大于305mOsm/L B.等于300mOsm/L C.小于300mOsm/L D.等于312mOsm/L E.大于312mOsm/L
A.眶外壁B.眶上壁C.眶上壁和眶外壁D.眶内壁E.眶下壁
A.2:4B.1:3C.1:2D.2:5E.2:3