GMAT Sentence Correction (SC) | Re: Scientists have found signs that moving water changed the

Here is the notes that I got from Thrursday's with Ron session on March, 26 2015 The use of AND

See the video from31:40 to48:00 below
https://vimeo.com/128740745

Analysis:
- 2 Actions: The scientists ..
Action (1) ... found evidence
Action (2) ... concluded XXXXX
Separate, or Two aspects of the same action
Here the actions are ..
found evidence .. (evaluated it for some time) .. then concluded it ..
So, Action (2) is not instantaneous with Action (1)

- Option (A),(B) usage
...

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