呕血最常见的原因是（）
A.胃底、食管静脉曲张破裂
B.食管癌
C.消化性溃疡
D.钩端螺旋体病
E.急性胃黏膜病变
参考答案：C
– What do you think Sally will be when she grows up?
– She loves science so much. I think she’ll be an .
A. engineer B. actor C. English teacher
120~400KV的X线的半价层用什么表示（）
A.铅
B.铝
C.铜
D.铜+铝
E.铅+铝
