-- You’d better turn to your elder sister.

-- ______. We haven’t talked to each other for quite a long time. I don’t think she’ll be willing to help me.

A．Never mind

B．No problem

C．I’d love to

D．I’d rather not

正常人吸入下列哪种混合气体时，肺通气量增加最明显

A．21%O₂和79%N₂
B．17%O₂和83%N₂
C．2%CO₂和98%O₂
D．20%CO₂和80%O₂
E．30%CO₂和70%O₂