钢筋混凝土结构的混凝土强度不应低于以下哪个级别()。
A.C10
B.C15
C.C20
D.C25
参考答案:C
解析:
参见第13题。
Only when he reached the teahouse ________ it was the same place he'd been in last year.(2011·全国Ⅰ)
A.he realized
B.he did realize
C.realized he
D.did he realize
在各种探伤方法中,()只能识别缺陷的性质,不直观,所以判断能力差。
A、X射线探伤
B、普通超声波探伤
C、磁粉探伤
D、γ射线探伤