设置在水沟中的（）接地极应用面积不小于0．6平方米、厚度不小于3mm的钢板制成。
A．辅助
B．主
C．局部
参考答案：C
阅读下面这幅华君武先生的漫画，然后说明画面内容并概括其寓意。
画面内容：________________________________
寓意：________________________________
This maths problem is _____ that one. [ ]
A. so easy as
B. as difficult as
C. much difficult than
D. less easier than
