大修前过热器和再热器首先进行（）和（）以后，才能进行防磨防爆检查工作。
参考答案：冲灰；清理管子外壁积灰
Their talks failed to reach any agreement and ______ now seems little hope of a settlement.
A．it
B．that
C．there
D．what
组成臂丛上干的神经是（）
A.颈5
B.颈5、6
C.颈7
D.颈8
E.颈8、胸1
