Paul had to write a history paper, ______ he couldn't find time to do it. [      ]

A. but

B. so

C. became

D. if

为预护火灾、爆炸、疾病等紧急情况，企业应()。

A.开展应对紧急情况的技术培训

B.制定紧急应对工作程序

C.保护现场等待有关人员处理

D.实施紧急情况模拟演拣