She opened her eyes with a start and was about to cry out ________ she heard her father urgently telling her to keep quiet.  

A．while

B．before

C．when

D．as

CT扫描对早期骨肉瘤诊断的价值在于显示（）

A.骨质增生硬化

B.细微骨质破坏

C.骨膜反应

D.软组织肿块

E.转移性病灶