对食管癌有帮助的诊断方法为（）
A.内镜伴活检
B.食管黏膜脱落细胞学检查
C.食管滴酸试验
D.食管压力测定
E.食管pH测定
参考答案：A, B
It is said that about ______of the books and magazines in the world______in English.
A. four-fifths;are written B fourth fives;are written
C, four fifth;were written D fourth fifths; were written
电离辐射中穿透能力最弱而电离能力最强的是（）
A.α射线
B.β射线
C.γ射线
D.中子
E.X射线
