《煤矿安全规程》第248条规定,火区内的氧气浓度降到()以下时,方可认为火区熄灭。
A、3%;
B、5%;
C、8%
参考答案:B
It was in that country_____ he studied for his doctor's degree____he fell in love with the girl. [ ]
A. that; that
B. which; where
C. where; that
D. where; where
与台班折旧费计算无关的是()。
A.残值率
B.物价上涨系数
C.耐用总台数
D.时间价值系数