A．Because it did not shoot far.

B．Because it did not bend easily.

C．Because it was too heavy.

D．Because its string was short.

硬膜外阻滞以下操作不妥的是（）

A.放管至15cm刻度处即退针

B.放管至13cm刻度处遇阻力可快速注水2ml再置管

C.如处理无效即拔出导管，旋转360°再置管

D.回抽导管血流不断应将导管外拔少许至回抽无血

E.回抽导管间断有血可将5mg麻黄碱稀释后注入