采煤工作面的回采工艺由哪些主要工序构成？
参考答案：主要由落煤、装煤、运煤、支护与采空区处理（回柱放顶）等五个工序组成。
— You could have turned to Mr. Smith, for he is always helpful.
— Yes, a whole day _____. [ ]
A. was wasted
B. had been wasted
C. would be wasted
D. will be wasted
施工组织设计中的降低成本额是指( )。
A．全部计划成本与全部目标成本的差额
B．全部承包成本与全部目标成本的差额
C．全部承包成本与全部计划成本的差额
D．全部实际成本与全部目标成本的差额
