Why did Su Xun name one son Su Shi and the other Su Zhe?

the word "Shi" is a part of a carriage. It seems useless, but it is not a complete carriage after it is removed. Su Shi was born uninhibited, so he offended many people. Su Xun was worried that he was in trouble, so he was named "Shi" together. "Zhe" is not used in people's work. However, after the death of people and horses, it will not be blamed on "Zhe". Therefore, Zhe is good at surviving between fortunes. Su Xun hopes that he will be safe and sound, so he named it Zhe.