关于肩胛骨正确的是（）

A.位于胸廓背面内上方

B.分二面三缘和三角

C.肩胛冈内侧端称肩峰

D.内侧角粗大有关节盂

E.下角平第5肋

Halon from extinguishers used on a class B fire，should be directed（）.

A.at the top of the flames

B.at the base of the fire near the edge

C.in short quick bursts

D.toward the upwind side of the fire