I have never seen ______ little birds eat ______ many insects in ______ a short time. [ ]

A.such; such; such

B.so; so; so

C.such; so; such

D.so; such; so

下列描述正确的是

A．骶管上通椎管

B．骶管位于骶骨正中

C．骶管裂孔形状部整齐

D．骶角为进行骶管麻醉的标志

E．下口为骶管裂孔