— Tom graduated from college at a very young age. 

— Oh, he _____ have been a very smart boy then. [ ]

A. could

B. should

C. might

D. must

低渗脱水的体液容量改变为（）。

A.细胞内、外液按比例减少

B.细胞内液显著减少，细胞外液正常

C.细胞外液显著减少，细胞内液轻度减少

D.细胞内液显著减少，细胞外液轻度减少

E.细胞外液减少，细胞内液正常