— I felt left out at the party last night.

— Really? _______, you should have said something.   [ ]

A. If possible        

B. If so    

C. If necessary    

D. If any

引起脑梗死最常见的原因是（）

A.脑细小动脉硬化

B.脑动脉粥样硬化

C.脑动脉栓塞

D.脑出血

E.肿瘤