英语语法题目,I ( ) that you were in Shanghai last month,otherwise

英语语法题目,
I ( ) that you were in Shanghai last month,otherwise I ( ) you.
A:had not known; would have visit
B:had not known; would visit
C:did not know; would have visited
D; did not know; would visit

C 这个句子是错综型的虚拟语气,注意前面一个分句不是虚拟,“我不知道你上个月在上海”这是事实,所以直接用过去式,后面的otherwise表示虚拟,意思是If I had known that you were ...,Iwould have visited you,跟过去事实相反,主句用would have done