Hardly had all the points that the teacher taught        down when the bell rang．

A．to aken

B．taking

C．taken

D．been taken

蛋白质的一级结构及高级结构决定于：（）

A.分子中氢键

B.分子中盐键

C.分子内部疏水键

D.氨基酸的组成及顺序

E.氨基酸残基的性质