don't know, didn't know, hadn't known, are, were -Hello!I____you

don't know, didn't know, hadn't known, are, were
-Hello!I____you___ in London. How long have you been here?
【正确答案】：didn' t knowwere
【题目解析】：【考点点击】本题考查一般过去体。【要点透析】根据句意可知,在说话之时,说话人已经知道对方在伦敦了,这句话指的是说话之前“我”不知道对方在伦敦,所以只能用过去体表示。