I felt as though we___each other for years.

I felt as though we had known each other for years.

本来是 we have knew each other for years.
这里有as though ，成为虚拟语气
虚拟语气用过去完成时代替现在完成时

c
是那样翻译。
考查对句子的理解。过去完成时的用法。虚拟语气。

过去的虚似语气用过去完成时。

c 本题考的是虚拟语气 as though 引导的从句的动作发生在过去，谓语动词用had +过去分词 如果指的是现在，谓语动词用过去式，如果指将来用would should could +动词原型，与主句的时态无关，
本题的从句发生在过去，所以选C

A,本题的重点是在考虚拟语气,是与过去事实相反的假设,本应用should have known, 但此处should 按英语习惯省略所以是A
意思是:我感觉就好象我们已经认识了好多年了.

考察as though 引导的虚拟语气，当主句是一般过去时，从句用过去完成时。
选c

选C。考察as though（仿佛，好像）引导的从句用虚拟语气，表示与过去事实相反，故从句谓语应用had known。