气态和蒸气态化学物质经呼吸道吸收，最主要的影响因素是

A．肺泡的通气量与血流量之比

B．化学物质的分子量

C．溶解度

D．血气分配系数

E．化学物质的沸点

If I _____ a million dollars I'd give it to medical research. [ ]

A. had

B. were

C. have

D. will have