if there had not been a hard layer of rock beneath the soil,they would have completed the job in a few hours.这句话为什么要用过去完
问题描述：
if there had not been a hard layer of rock beneath the soil,they would have completed the job in a few hours.这句话为什么要用过去完成时呢?为什么不用一般过去式呢?改成这样 if there were not a hard layer of rock beneath the soil,they would have completed the job in a few hours这样不是更好吗?为什么呢?
用过去完成时他语境更加强调了什么呢？
答
虚拟语气,条件句要往后推一个时态,一般过去式变为过去完成时.这里是语法问题,跟语义关系不大.那现在时就要写成过去式？对的。现在时要写成过去式过去式要写成过去完成时那现在完成时也是写成过去完成时吗？对的，跟主句是过去式的从句动词变位类似。