If you don't know the answer to something,  you say: "_______" [ ]

A. Sorry, I don't understand.

B. I'm sorry. I don't know.

C. Can you speak English?

D. Excuse me. How do you say that in English?

在胸部右前斜位片反映有心室增大的早期征象是（）

A.肺动脉圆锥部膨突

B.心前缘膨隆

C.心前下间隙缩小

D.膈面延长

E.无特异性