点A（﹣3，m）和点B（n，2）关于原点对称，则m+n=____ ．

英国哲学家罗素在评论雅典政治时指出：“我们习惯于指责雅典人的‘民主’是不充分的，因为它排除了妇女和奴隶。但我们并不总能意识到，它比起当政府的范围扩大时所可能有的民主来，要更加民主，因为每位公民对一个问题都能够解决。”材料意在说明（   ）

任务型阅读

    My name is George．I'm from England．Now I'm studying in Germany．I get to school at 7：30 every morning．I find many of my schoolmates come to school by bike．  ①   

    This is an interesting thing for me．In England people usually drive，take a bus or walk somewhere，for example，to school．In Germany, I often see people，even people over eighty years old going somewhere by bike．It makes me think：  ②   

My father gives the answer．We are living in Northern Germany．It is very flat(平坦的).So it is easy for people here to go somewhere quickly by bike .And it's cheaper than(比…….便宜)going by car or by bus．Also,it's good for the environment(环境)．

    I like riding bikes now．   ③    When I go back to England，I will ride more and ask my friends to ride with me．I think they will like tiding bikes，too．

根据材料内容完成下列任务。

Bob ____________ beef, fish ____________ onions.