I tried to think of an example, but got lost. I believe "But where is the fork?" will more likely be "Но где вилка?"
You use и in one phrase like: мама и папа. And you use а if there're two different phrases like: Это мама и папа, а это бабушка. If you translate а as "and" or "but" depends on the context, so you can use both as well.
When do we translate the letter "а" in sentence, because I see sometimes don't translate it.
It was not wrong, but the choice between "and" and "but" depends on the context.
- и = and
- но = but
- а = and OR but (depending on the context)