下列哪几项是早期食管癌的X线表现()
A.局限性粘膜皱襞增粗和断裂
B.局限性管壁僵硬
C.小龛影
D.小的充盈缺损
E.食管上段不同程度扩张
参考答案:A, B, C, D
用四舍五入法按要求对0.05019分别取近似值,其中错误的是( )
A.0.1(精确到0.1)
B.0.05(精确到千分位)
C.0.05(精确到百分位)
D.0.0502(精确到0.0001)
We must _______ to improve our English.[ ]
A. do our well
B. do our best
C. do one's better
D. do one's best