维护统治秩序与惩罚犯罪的客观需要，是警察产生的社会条件。 ( )
参考答案：对
The famous singer has agreed _____ the prizes at the prize giving ceremony.[ ]
A. to present
B. present
C. to presenting
D. presenting
预防肺结核的最主要措施是
A．禁止随地吐痰B．健全防痨组织C．隔离和有效治疗排菌病人D．加强登记管理E．接种卡介苗，化疗
