分类：教育/科学-学习帮助
问题：一道高一英语选择题Hello!I_____you_____inL 
Hello!I _____ you _____ in London.How long have you been here?A.don't know;were    B.hadn't known;are.haven't known;are  D.didn't know;were
回答：D
因为How long have you been here
所以用were，BC排除掉
另外我过去不知道，现在知道了。所以don't know要用过去是