问一个问题哦~~

2452310178zzw

关于prep的一个问题， 可能有点弱，不过还是麻烦大家看看吧~~
196.(GWD-1-Q41)
Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria take an active part in the process.
A.as a method of the extraction of minerals, it was well established

B.as a method of the extraction of minerals well established

C.was a well-established method of mineral extraction

D.was a well-established method of extracting mineral that was(C)

E.had been a method of mineral extraction, well established

我想问为什么E选项不能用过去完成呢？后面明明有过去式的呀？！

2452310178zzw

自己顶顶

Sofiaxy

我想，可能陈述的是一个过去的客观事实，并不是两个动作的对比吧~
其实，对于过去完成时、过去时，我自己也不太分得很清楚，还希望有高人指点啊！

酩茗

had been 的话就说明它在18century以后就不用了。。但是后面又说了225years ago 这明显不对。
LZ要注意这个过去完成时的意义。。。
personal opinion。。。