下列对应关系正确的是（  ）

①冰冻三尺，非一日之寒——真理是具体的、有条件的

②野火烧不尽，春风吹又生——认识具有反复性和无限性

③纸上得来终觉浅，绝知此事要躬行——实践是认识的来源

④真理之川从他的错误之沟渠中通过——真理和谬误是相伴而行的

一辆汽车以20m/s的速度沿平直的公路从甲地开往乙地，又以30m/s的速度从乙地开往丙地．已知甲、乙两地间的距离与乙、丙两地间的距离相等，求该汽车在从甲地开往丙地的过程中平均速度的大小．

有一位同学是这样解的： $\overline{v}$ = $\frac{20+30}{2}$  m/s=25m/s，请问上述解法正确吗？为什么？应该如何解？

2015年6月，中国某企业承建了越南富叻一期风电项目，总装机24MW。下图为富叻位置示意图。据此完成以下问题。

阅读理解

    I'm Li Ming．The holidays always make me happy．Last summer holiday,I went to Paris with my mother by plane．We went there to visit my uncle．He met us at the airport．

    My uncle took us to visit the Louvre Museum by underground．I saw a lot of famous things．I enjoyed many old pictures in it．The pictures were very creative(有创意的)．We also visited the Eiffel Tower．It is the famous symbol(标志)of Paris．One evening，my uncle took us to eat good food and go shopping．My mother bought many clothes-some for her,and some for my sister．

We stayed in Paris for about half a month.The trip gave me lots of fun.I will remember it.

根据材料内容选择最佳答案。