نوشته شده توسط intellectual2009 [ برای مشاهده لینک ، با نام کاربری خود وارد شوید یا ثبت نام کنید ]The sentence you've mentioned is not passive, don't forget in passive tenses we use "to be" . The passive form of that sentence can be
.A taxi couldn't have been taken for him
I don't see any relevance between this passive form and that structure. I think if we use passive tenses we won't be able to use this form because the meaning is not unreal past!!! It is unreal past tense.. so it's just past tense