用代入法解方程组$\left\{\begin{array}{c}7x-2y=3\left(1\right)\\ x-2y=-12\left(2\right)\end{array}\right.$有以下步骤：

①：由（1），得y=$\frac{7x-3}{2}$（3）；

②：由（3）代入（1），得7x-2×$\frac{7x-3}{2}$=3；

③：整理得3=3；
④：∴x可取一切有理数，原方程组有无数个解
以上解法，造成错误的一步是（　　）

阅读下列材料，回答问题：

（1）上图中的人物是我国春秋时期伟大的思想家、教育家。请问他是谁？是什么学派的创始人？
（2）作为思想家，他的思想主要是什么？作为教育家，他有哪些主张？（两点即可）
（3）站在今天，我们看待他的思想应持一种怎么样的态度？

    More and more people around the world are joining in dangerous sports. Some people climbed the highest mountains; some traveled into unknown parts of the world; some sailed small boats across the largest sea. Now some people begin to look for new excitement.

    Bungee jumping (蹦极) and motorcycle racing (摩托车赛) are quite dangerous sports. Bungee jumping only lasts for a few minutes or even seconds. You jump from a high place, about 200 meters above the ground, and there is a rubber band (橡胶带子) tied to your legs. When you jump down, the rubber band pulls you up. About 2,000,000 people around the world have tried bungee jumping.

    Why do people join in these dangerous sports? Some scientists say that it is because modern life has become safe and it is not interesting. In the past, people lived in danger. They had to go out and look for food, and life was like a fight but was interesting.

    Many people think that there is little excitement in life. They live and work in safe places, buy food in shops, and there are doctors and hospitals to look after them if they become ill.