Not until I was standing on the edge of death ____ how much I wanted to live. [    ]

A. I realized    

B. did I realize    

C. I had realized  

D. had I realized

根据Ag-Cu二元相图(如图所示)，

(1)写出图中的液相、固相线、α和β相的溶解度曲线及三相恒温转变线；
(2)计算ω(Cu)=60%的Ag-Cu合金(y’y线)在M点对应温度下液相和β相的相对量；
(3)画出上述合金的冷却曲线及室温组织示意图。