各省、自治区、直辖市划定的基本农田应当占本行政区内耕地的( )以上。
A．70%
B．75%
C．80%
D．85%
参考答案：C
So difficult did I find ___ to work out the problem that I decided to ask my partner for help.
A．myself
B．us
C．it
D．that
在民用建筑节能施工中，施工单位的职责是什么？
