Jump to content
Urch Forums

Leaching, the recovery


mehrak

Recommended Posts

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

OA:C

 

why not E? because “Leaching” is happened earlier than the second part of the statement. Can anybody explain plz?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...