— Nowadays few people live in a place permanently, and population mobility is a ______.  

— Yes. The present world is more on the _______ than ever before. [      ]

A. tendency; go

B. trend; move

C. phenomenon; move

D. fashion; go

我国最常见的咯血原因是（）

A.支气管扩张

B.肺结核

C.二尖瓣狭窄

D.肺脓肿

E.支气管肺癌