当陷坑发生在（）时，可将陷坑填满后再抛填黏性土加以封堵和帮宽堤身。
A.背水坡
B.堤顶
C.坡脚外
D.堤身单薄的临水坡
参考答案：D
后付年金
The environmentalists said wild goats' _____ on the vast grasslands was a good indication of the better
environment.[ ]
A. escape
B. absence
C. attendance
D. appearance
