I didn't go to school yesterday，I was ill.
修改错误：
I didn't go to school yesterday，because I was ill.
昨天我没去上学，因为我病了。
修改原因：
because引导的原因状语从句一般放于主句的后面，because从句位于句首时要用逗号分开，放在句末时，可不用逗号分...
原句：
I didn't go to school yesterday，I was ill.
修改：
I didn't go to school yesterday，because I was ill.
昨天我没去上学，因为我病了。
原因：
because引导的原因状语从句一般放于主句的后面，because从句位于句首时要用逗号分开，放在句末时，可不用逗号分开...
