Learn Polish: Czyżby to była prawda? - Could it be that this is true?

While czy simply asks a neutral yes/no question, czyżby adds a strong layer of doubt, surprise, or disbelief. It transforms a basic 'Is this true?' into 'Could it possibly be true?' or 'Is it really true?'.

The English translation is in the present tense ('is true'), so why does the Polish sentence use the past tense verb była?

It is actually the conditional mood! The word czyżby ends with the conditional particle -by. When you pair czyżby with the past tense form była, they work together to create a conditional meaning, functionally identical to byłaby (would be). This gives the sentence its hypothetical 'Could it be...' feeling about a present situation.

Why is the verb była in the feminine form when the subject is the neuter pronoun to?

When you use to as a dummy subject to identify something (similar to saying 'this is X' in English), the verb być (to be) agrees in gender with the noun that follows it, not with the pronoun to. Because the noun prawda is feminine, the verb takes the feminine form była instead of the neuter było.

Why is prawda in the nominative case here? Doesn't the verb być usually require the instrumental case for nouns?