堤防断面图中主要标示了地面线、堤坡线、（）、加固区顶面线等内容。
A.临河堤肩线
B.背河堤肩线
C.堤脚线
D.堤顶线
参考答案：D
水阀在安装方向上应注意些什么？
Thanks to the Internet, the world seems to become _______. [ ]
A. smaller and smaller
B. small and small
C. more and more small
D. smallest and smallest
