that 在句子中做什么成分
问题描述：
that 在句子中做什么成分
It happened once ,however ,some 70 years ago ,that the gold cup was stolen a few days before the race.
答
你把插入语（however,some 70 years ago）去掉,变成It happened once that……
这句话是主语从句,It是形式主语,that作从句连词