请问选 A还是B?这里的could可以算是过去式吗?

题目

请问选 A还是B?这里的could可以算是过去式吗?
Could you tell me ____?He is wanted by the head teacher.
Sorry,I've no idea.But he ___ here just now.
A:where Tim was,was B:where Tim is,was

答案

答案选B 因为could 表礼貌,不表过去.所以用where Tim is 而下面答语里有just now 是表过去,所以用was ,明白了吗