有压隧洞
参考答案：
指洞内充满水，没有自由水面，断面形状一般为圆形的过水隧洞。
He began to work there ______________. [ ]
A. on his fifty
B. at ages of fifty
C. when he fifty
D. in his fifties
当石膏砌块砌体长度大于（）m时，砌体顶与梁或顶板应有拉结，当砌体长度超过层高（）时，应设置钢筋混凝土枸造柱。
