The class went on with the story（ ） they had left it before the holiday.这个中间应该填什么 如果用WHICH的话 left 后面为什么加it?

The class went on with the story（ ） they had left it before the holiday.这个中间应该填什么 如果用WHICH的话 left 后面为什么加it?
The class went on with the story（ ） they had left it before the holiday.
这个中间应该填什么 如果用WHICH的话 left 后面为什么加it?

The class went on with the story（ ） they had left it before the holiday.这个中间应该填什么 如果用WHICH的话 left 后面为什么加it?
填where（副词）,表示story 上次被暂停的地方