there were是什么成分?what引导什么句?what 前面怎么有 介词in?

1、我们先划分一下句子成分,
Aunt Harriet ：主语；discovered 是动词,所以充当谓语；则
that引导的是一个宾语从句（下面简称宾从）,即 “there were piles of empty wine bottles of all shapes and sizes neatly stacked in what had once been Bessie's wardrobe”.所以there are是宾从的主语.
2、分析句子是也要看句子的意思：哈里特大妈发现在贝茜的衣橱里整齐地堆放着形状大小各异的空葡萄酒瓶.
3、其中需注意的是,stacked in是一个固定短语,意思是堆放在.
4、所以 what had once been Bessie's wardrobe是一个地点状语从句,而had once been 是谓语,Bessie's wardrobe是宾语,应该缺主语吧,所以what是主语.
不清楚的话还可以找我~
再问： 谢谢只要你不嫌麻烦，还想问一下这句是接着上面那句的they had mysteriously found their way there from the wine cellar。即（Aunt Harriet discovered that there were piles of empty wine bottles of all shapes and sizes neatly stacked in what had once been Bessie's wardrobe.they had mysteriously found their way there from the wine cellar）中的they是指人还是指酒瓶？ found 在这里面是什么意思呀？
再答： 我搜了一下，这是新3的是吧，我看了一下原文。 翻译：这些酒瓶神不知鬼不觉地从酒窖来到了这里。 they：是酒瓶。found创立，建立。 直译：这些酒瓶秘密地创立了他们自己的方式来到那里，从酒窖。 希望对你有帮助~~~