he felt ill,so he went to the hospital是并列句还是复合句?

1。he felt ill, so he went to the hospital因为有连词so的存在,因此为并列句且前后为因果关系。2。he went to the hospital because（as) he felt ill。是复合句。因为句中的because引导时间状语从句,实际上是一个句子。