A-A+
______ has been mentioned above the size of a
问题详情
______ has been mentioned above, the size of a canal depends upon the kind of boats going through it.
A．What
B．This
C．As
D．It
参考答案
正确答案：C
解析：在本题中，as用作关系代词，引导的是非限定性的定语从句。同类用法更为常见的表达又如As is known to all，．．．。本题中的其他选项均没有这样的用法，故都应该被排除掉。
