引起自发性气胸最常见的疾病是（）

A.慢性阻塞性肺疾病

B.肺结核

C.肺癌

D.支气管扩张

E.肺尘埃沉着症

.It was the practice _____ he got abroad _____ made him a good English speaker.

A．what; that

B．that; that

C．that; which

D．which; that