食管癌前后对穿野定位在肿瘤长度的上下界各放()
A、1.0C、m
B、1.5C、m
C、2.0C、m
D、2.5C、m
E、3.0C、m
参考答案：E
In this park,the number of visitors is strictly _____ to avoid damaging the environment. [ ]
A. limited
B. encouraged
C. expected
D. hoped
诊断鸡马立克氏病必须与（）鉴别。
A．鸡淋巴白血病
B.鸡白痢
C．鸡新城疫
