Corruption is _______ problem in countries across the world, with developing countries often believed to be more serious, although there is no evidence to suggest this is _______case.

A．a; the

B．the; a

C．不填; the

D．a; a

恶性骨肿瘤的X线表现特征是（）。

A.边缘不清楚，骨质增生，无骨膜反应

B.边缘不清楚，骨质破坏.无骨膜反应

C.边缘清楚，骨质破坏，骨膜反应明显

D.边缘清楚，骨质增生，无骨膜反应

E.边缘不清楚，骨质破坏，骨膜反应明显