______ herself in looking after the newly-born twins, she had to sacrifice her career to stay with her kids.

A．Occupied

B．Being occupied

C．Having been occupied

D．Occupying

下列哪个性质是氨基酸和蛋白质所共有的（）

A.胶体性质

B.两性性质

C.变性性质

D.沉淀反应

E.双缩脲反应