我市在创建全国文明城市过程中，决定购买A，B两种树苗对某路段道路进行绿化改造，已知购买A种树苗8棵，B种树苗3棵，需要950元；若购买A种树苗5棵，B种树苗6棵，则需要800元．

（1）求购买A，B两种树苗每棵各需多少元？

（2）考虑到绿化效果和资金周转，购进A种树苗不能少于50棵，且用于购买这两种树苗的资金不能超过7650元，若购进这两种树苗共100棵，则有哪几种购买方案？

（3）某包工队承包种植任务，若种好一棵A种树苗可获工钱30元，种好一棵B种树苗可获工钱20元，在第（2）问的各种购买方案中，种好这100棵树苗，哪一种购买方案所付的种植工钱最少？最少工钱是多少元？

读“俄罗斯图”，回答各题．

短文改错

下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏字符号（∧），并在其下面写上该加的词。

删除：把多余的词用斜线（﹨）划掉。

修改：在错的词下画一横线，并在该词下面写出修改后的词。

注意：1.每处错误及其修改均仅限一词；

2.只允许修改10处，多者（从第11处起）不计分。

My old classroom was interesting because three side of the classroom were made from glass. I enjoyed sit close to the windows and looking at the view. On the left-hand side of the class, I could easy see the football field. In the mornings, it was full of students exercising. The view from the back of the classroom is also splendid. Close to the school there was a beautiful park with many trees around them. Farther in the distance, I could not enjoy the view of snowy mountains. On the right side of the class was the road. I was always interested to see the drivers in hurry in the morning. The position of the classroom with its view made me felt like I was dreaming. If I was only a child when I studied in that classroom, I will never forget it.

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一段长0.2 m，通过2.5 A电流的直导线，关于在磁感应强度为B的匀强磁场中所受安培力F的情况，正确的是(　)