---_____ of them knows Japanese, so I have to ask a third person for help.

---You’d better ask Tom for help. He is good at Japanese.

A．Neither

B．All

C．Both

D．None

下列关于气管和主支气管错误的描述是（）

A.气管位于食管前方

B.气管于胸骨角平面分为左、右主支气管

C.全程分为三段

D.右主支气管比左侧粗短

E.颈段气管较胸段的长