I found my books I had left it.为啥用where不用the

I found my books I had left it.为啥用where不用the 怎么分析It was where i had left them that i found my lost books. i found my unbrella where i had left it The other day ,I found my wallet where I had been leaving it where is the pencil?用I don't know 为啥不用I can't see it It was __ that i found my books.是选in the place that i had le It was not until I got home ____ I found that I had left my I found my books_________I had left them.A.in which B.where如 Alice left the book where she had found it. the other day,I found my banknote__ I had left some weeks be I found my book where I had left them,这个句子是从句吗,是什么从句,修饰哪个... I had left it on the chair.That's where I _____it.