hesearchedforhispeneverywherebutinvain,finallyherealizedthatitonhisdeskallthetime.A)hadbeenlyingB)hasbeenlyingC)hadbeenlainD)waslain请问答案为什么选A呢,希望可以得到详细具体的解答,如果有需要

Question

he searched for his pen everywhere but in vain ,finally he realized that it ____ on his desk all the time.
A)had been lying
B)has been lying
C)had been lain
D)was lain
请问答案为什么选A呢,希望可以得到详细具体的解答,如果有需要的话可以追加分数,

Answer 1

首先he realized为过去式,所以后面pen在桌子上应是过去的过去,（也就是在他意识到之前就一直在桌子上了）故用过去完成,而后面有all the time (一直）所以用完成进行时.