Pikuai answers~
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How to identify a effect/change:
Usually they'll use words such as "then, after, however" Then state a new claim. for example. "I worked the night shift, now I'm always tired!" The cause was working the night shift and the effect is being tired. Now on to the answer.
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Answer:
It had given him in-lightment on how the world really was, compared to how he was oblivious to before learning how to read. He had finally been able to understand the horrible things that were wrote on ads and signs.
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Why I say this/evidence:
"I envied my fellow--for their stup---" supporting my claim " He had finally been able to understand the horrible things that were wrote on ads and signs."
"It opened my eyes to the horrible pit..." supporting my claim "It had given him in-lightment on how the world really was, compared to how he was oblivious to before learning how to read"
I hope this helps! Have an amazing day~