hello!i___you ___in London .how long have you been here?

hello!i___you ___in London .how long have you been here?
hello!i___you ___in london .how long have you been here?
A.don't konw; were
B.hadn't known; are
C.haven't known; are
D.didn't know; were
答案选的是D.句尾是here,证明说话的地点就在London.为什么第二个空格要用were?you were in London 意思是指过去你在London,而不是现在在London啊.

首先here并不是最关键,这个句子要根据语意来判断
how long have you been here?
译为：你已经在伦敦（here）住了多久?
have been 现在完成时是指：从过去的某一段时间到现在,been表延续性
所以要用didn't know; were,译为：我不知道你在伦敦（语境是过去的某段时间一直不知道）