GIVE ANSWERS - Русский язык

The question is not clear, what do you mean: when "o" is "a"? Show in example, please.

for the most part it is memorization. cot is something you lay on, caught is an animal in a cage. same sound memory

Example

it depends on the word you mean

Like in "хорошо" (well)? Both unstressed letters "o" are pronounced like unstressed "a" in this case.

Well, in some regions even unstressed "o" will forever remain "o" to be honest so it's all up to you.

I'm not understand to you, What do you mean?