Not until all the fish died in the river ________ how serious the pollution was.

A．did the villagers realize

B．the villagers realized

C．the villagers did realize

D．didn’t the villagers realize

下列征象提示骨软骨瘤恶变的是（）。

A.软骨帽内钙化

B.肿瘤较大，压迫邻近骨骼

C.瘤体出现骨皮质或边缘部骨质破坏

D.瘤体有宽基底蒂与骨相连

E.病灶呈分叶状