城市桥梁基坑,喷射混凝土的强度必须满足设计要求且不低于20MPa,喷射厚度不小于( )。
A.50mm
B.60mm
C.70mm
D.80mm
参考答案:C
—_________ is Mike staying?
—He is staying for 2 weeks. [ ]
A. How often
B. How long
C. How much
D. How soon
隐色体电位绝对值较小的染料,就是比较容易还原的染料;反之,绝对值较大的染料较难还原。