在正式开槽定出沟管中心线前应（）。
A.申请掘路执照
B.开挖样洞
C.核对地下管网
D.A+B+C
参考答案：D
--What heavy snow! Is everyone here today?
--Yes. __________of us is late for school.
A．Either
B．Neither
C．None
D．Both
But for his help, we wouldn’t have succeeded. So we ______ his timely aid.
A．distributed
B．contributed
C．acknowledged
D．admitted
