— You must get excited about going to France to study oil painting.

— ________, but I'm afraid I can't do well because my French is too poor. [ ]

A. I don't know yet  

B. Certainly not

C. Well, I ought to have 

D. All right

肺动脉瓣关闭不全最常见的病因是（）

A.特发性肺动脉扩张

B.继发于肺动脉高压所致肺动脉干的根部扩张

C.肺动脉瓣病变如风湿性心脏病

D.感染性心内膜炎致肺动脉瓣穿孔

E.马凡氏综合征致肺动脉扩张