The government _______ a committee to deal with the accident which happened there two days ago.

A. appreciated      

B. appointed        

C. appraised        

D. applied

“一铲能铲千层岭,一担能挑两座山,一炮能翻万丈崖,一钻能通九道湾。两只巨手提江河,霎时挂在高山尖。”这首民谣创作的时代背景应是                                   

A．延安大生产运动

B．农业合作化高潮

C．“大跃进”运动

D．土地改革