Hi Abhishek,
abhishek.shanker wrote:
Joe LEARNED about an epoch in which dinosaurs HAD WALKED the earth - Wrong
If you look at context of the sentence, you know that dinosaurs existed before Joe. The past action is obvious and does not require the use of past perfect.
abhishek.shanker wrote:
My reasoning: Action WALKED if not completed then "LEARNING" cannot take place. Can some one please clarify?
Correct but using simple past, it does not mean that the action "walked" did not complete.
abhishek.shanker wrote:
Also how do we decide if an action has impact on other.
You have to look at the meaning of the sentence and decide accordingly.
Regards
Sunil