确定两堤肩线的位置时应考虑的因素不包括()。
A.堤顶宽度一致
B.堤肩线顺直
C.采用定型曲线
D.堤肩线平滑过渡
参考答案:C
The weather turned out to be fine yesterday. I the trouble to carry my umbrella with me.
A.should have taken
B.could have taken
C.needn’t have taken
D.mustn’t have taken
试解释数据独立性的概念及其含义。