外伤性无虹膜
参考答案：
当虹膜睫状体挫伤较重，有的整个虹膜从根部完全离断，称外伤性无虹膜。
—Shall we go swimming this afternoon?
—Sorry, I ________. I have lots of homework to do. [ ]
A. mustn't
B. needn't
C. may not
D. can't
固定管板式换热器有两块管板而U型管式换热器只有一块管板。
