英语虚拟语气题

英语虚拟语气题
57.如果时间能够倒流几十年,我真希望和你们一样成为这所名校的学生.（go back）
57.If time could go back several decades,I would really like to be a student of this world-famous university just like you.
如果时间能够倒流是对现在虚拟,从句应该用did,主句应该用would do,为什么答案的从句是could go back 不是应该用went back吗?