Do you know是主句，引导下面的who John Lennon was who，where，what引导的从句要倒装
do是助动词，帮助句子构成疑问句，you是句子的主语，know是谓语，后面是由who引导的一个宾语从句
Do you know 主句who John Lennon was 宾语从句，做动词know的宾语
