so前面可以加逗号吗?

问题描述:

so前面可以加逗号吗?
He was ill yesterday ,he did not come to school.

当然可以啊,加逗号分成两个短句嘛.那个可以是so 吗?可以,因为这个句子是因果关系呀。可是答案是and不是so