I knew 是主谓,that是引导词引导宾语从句,整个句子that we had lived on ST.Marks square,Philadelphia作宾语,because引导状语,整个句子because the next winter we lived near ST.Mark Square and still knew people who lived there.作状语,属于原因状语从句,其中
the next winter 作整个原因状语从句的时间状语
we lived near ST.Mark Square 与still knew people who lived there是两个并列句,后面句子的主语是we,也就是we still knew people who lived there,其中who lived there作前面一个单词people的定语从句.
这个一个复合句,里面包含了从句.其主要结构就是 主谓宾结构.