氧化氮分离器的稀酸浓度大约是()。
A.20%
B.34%
C.45%
D.65%
参考答案:B
Do you know how many people ______ the big fire last week? [ ]
A. lived
B. survived
C. stayed
D. continued
在工程量清单模式下,宜采用()。
A.固定总价合同
B.单价合同
C.可调总价合同
D.成本加酬金合同