直肠癌出现便血，鉴别诊断中不应有：（）
A.肛 * * 肥大
B.肠炎
C.痢疾
D.内痔
E.直肠息肉
参考答案：A
—Could you please tell us_________ the World EXPO in Shanghai? – In July.
A．when you visited
B．why you visited
C．when did you visit
D．why did you visit
负强化就是惩罚那些与组织目标不一致的行为，以使这些行为减少。
