— I left my handbag  on the train, but luckily someone gave it  to a railway official.  

— How unbelievable to get it back! I mean, someone _____ it.     [ ]

A. will have stolen    

B. might have stolen      

C. should have stolen      

D. must have stolen

发生重特大灾害事故，要启动（）机制，社会相关联动力量也要投入行动。

A、抢险救灾

B、消防救援

C、城市应急救援

D、联合救援