老年人鼻出血多见于()。
A.little's区
B.吴氏鼻-鼻咽静脉丛
C.咽隐窝
D.鼻咽纤维血管瘤
E.鼻中隔前部
参考答案:B
Her parents _____ lunch at home. [ ]
A. doesn't have
B. haven't
C. hasn't
D. don't have
水轮机转轮为什么会产生裂纹?反击型水轮机转轮在哪些部位易发生裂纹?