天然状态砂土的密实度一般用（）来测定。（）
A.载荷试验
B.轻便触探
C.十字板剪切试验
D.标准贯入
参考答案：D
He made another wonderful discovery, ______ of great importance to science.
A．which I think it is
B．which I think is
C．which I think
D．I think which is
窄面凹陷属于（）缺陷、纵向裂纹属于表面缺陷、对角线裂纹属于内部缺陷。
