①附中高一年级聪明的学生；

②直角坐标系中横、纵坐标相等的点；

③不小于3的正整数；

④$\sqrt{3}$的近似值；

考察以上能组成一个集合的是____ 

根据短文内容选择正确答案。

    Mrs. Smith is Jim's mother. She loves her family very much.  She goes to the store every day. She often buys food, fruit and clothes for Jim and her husband. Now many clothes are on sale at Renmin Clothes Store. They are very cheap. Mrs. Smith comes to the store and she wants to buy some clothes for her family. There they have sweaters in all colors for ￥15 each and sports shoes for only ￥28. Mrs. Smith likes the red sweater and she buys one for herself. She buys a pair of sports shoes for her son. The great T-shirts in the store are just ￥18!  She buys a white one for Mr. Smith. And that's not all. The socks, in all colors, are ￥2 each. She buys the socks in many colors for her family. She is really a Rood mother and a good wife (妻子).