▲问题解答：

这样的时态搭配合理。

1. 正如English老师所说，从句中的 were lying 可以表示“多次撒谎”或“总是撒谎”；但更大的可能是表示“当时（强调当时时间的特定性）在撒谎”。另外，从句部分也可以用过去时（lied)，不过用过去时就不能表示“特定的场合进行着的动作”这一意味。

2. 主句的完成时表示已经是一个“事后从犯（法律术语，它不同于犯罪过程中的从犯）”，而且从开始撒谎以来一直是个事后从犯。

▲老外观点（节选）：

老外1(印度佬）：I understand the sentence as referring to a series of lies that occurred on more than one occasion. That's probably why "were lying" was used.
              In the second part, "you have been" is correct - the present perfect continuous shows that the person was an accessory after the fact and continues to be one. 

老外2（英国佬）：there's nothing to show repeated lying or lying over a long period of time. It's normal use of the continuous form（进行式）: When you said something, you were lying to the police (on that occasion), then...
              With the simple past form（过去式） it sounds somehow more vague （模糊的）and less likely to refer to one particular occasion: If you lied to the police (at some time in the past) , then you have been an accessory after the fact for all these years. 这句中，老外的意思是进行时更能表示特定场合发生的动作。

（如果看不懂英语的话，请继续提问。）

▲参考翻译：

If you were lying to the police, then you have been an accessory after the fact for all these years.

1. 如果你之前老是向警方撒谎，那么这么多来，你就是一个“事后从犯”。（这种意思可能性较小。）

2. 如果你当时是在对警方撒谎，那么这么多年来，你就一直是个“事后从犯”。（这种意思的可能性很大。）

▲要点总结：

      总之，从句的进行时表示当时"在撒谎"这个事实，主句完成时表示一种"状态的延续"（注：完成时也可以表示动作或状态的延续, 翻译为汉语的话可以加上“一直”。如，he has been a teacher since he graduated.）。Hope it helps.Good luck to you.

回答如下：

(1) 以上属于(进行时态的）阶段进行用法（在过去阶段一直进行的动作行为）。

(2) were lying to the police 表示在过去阶段一直处于向警察撒谎的一个状态，

(3) 中文翻译：如果在过去（阶段）你一直都向警察撒谎...那么所有这些年来就一直是犯罪事实背后的同谋/帮凶/从犯。