— Why do you think ______?

— He could ______ for exercise.

A．is the man running, run

B．the man is running, be running

C．does the man run, run

D．the man runs, be running

对于正常人，下列说法错误的是（）。

A.体液容量相对恒定

B.体液电解质相对恒定

C.体液渗透压相对恒定

D.体液酸碱度相对恒定

E.体液总量与年龄无关