. Now everyone is concerned about how to conquer the economic crisis _______ is very important for us to be able to preserve our standard of living.

A．which success

B．its success

C．the success of which

D．the success of it

具有四级结构的蛋白质的特征是（）。

A.分子中含有辅基

B.胰岛素具有四级结构

C.每条多肽链都具有独立的生物学活性

D.依赖肽键维系四级结构的稳定性

E.由两条或两条以上具有三级结构的多肽链组成