钢筋混凝土空心桥墩的最小壁厚不宜小于( )cm。
A．20
B．30
C．50
D．40
参考答案：B
I don't have _____ books. I think Mary has _____. [ ]
A. some; some
B. any; any
C. any; some
D. some; any
未经化学处理的海鸟粪(每包毛重10kg)
