下列省区中全部位于秦岭—淮河以北的一组是（      ）

小小阅读我做主。

       秋天的雨，有一盒五彩缤纷的颜料。你看，它把黄色给了银杏树，黄黄的叶子像一把把小扇子，扇哪扇哪，扇走了夏天的炎热。它把红色给了枫树，红红的枫叶像一枚枚邮票，飘哇飘哇，邮来了秋天的凉爽。金黄色是给田野的，看，田野像金色的海洋。橙红色是给果树的，橘子、柿子你挤我碰，争着要人们去摘呢！菊花仙子得到的颜色就更多了，紫红的、淡黄的、雪白的……美丽的菊花在秋雨里频频点头。

    We go to school from Monday to Friday. We have four classes in the____and three in the afternoon. We have____things to do after class. On Monday and____afternoon we have P.E. On Wednesday morning some of us have a singing class. On____morning some have a drawing class. On Friday____we practice speaking English.

若2a=3b=4c，且abc≠0，则$\frac{a+b}{c-2b}$的值是(    )