.------ You seem unhappy today, Jane. ______

------ I lost my new bike yesterday.

A．How’s that?

B．What’s on?

C．What a pity!

D．Did you sleep well last night?

肺泡外缠绕着丰富的毛细血管网，这有利于（　　）

A．肺的生长

B．肺泡与血液间的气体交换

C．气体在血液里的运输

D．组织里的气体交换