Mary is ill,____she can't go to school.

Mary is ill,____she can't go to school.
Mary is ill,____she can't go to school.

Mary is ill,____she can't go to school.
so
表示因果关系 前半句表示原因 后半句结果

so

Mary is ill,_so_ she can't go to school.

SO she can't go to school
THAT'S WHY she can't go to school
很多可以填啊

所以
so或as a result