关于GWD1-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

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

答案是C，但是不知A和E的主要问题在哪，C感觉和后面接不上啊

Leaching (主语), the recovery of copper from the drainage water of mines(同位语作插入语), was (谓语) a well-established method of mineral extraction as early as the eighteenth century, but(转折-代表后为完整的句子，而且but前面应该也为完整的句子，故B错) until about 25 years ago miners did not realize that bacteria take an active part in the process.

A中 Leaching, as a method of the extraction of minerals, it was well established ， it 和 Leaching 冲突了

C和E的差异为时态，the eighteenth century 应该用过去时

同位语经常是考点

 过去时态用在过去的过去

up