Learn Russian: Мне было страшно: я слышал плач то ли во сне, то ли наяву. - I was scared: I heard weeping either in a dream or in reality.

While или ..., или ... simply presents a choice of either/or, the то ли construction expresses the speaker's own doubt, confusion, or inability to remember. It translates closer to "I couldn't tell whether it was X or Y." Since the speaker here is disoriented, то ли ..., то ли ... perfectly captures that psychological state.

Why does the sentence use Мне было страшно instead of a direct translation like Я был страшен?

Russian typically expresses emotional and physical states (like being scared, cold, or sad) using an impersonal construction. The person experiencing the feeling goes in the Dative case (мне). If you used the Nominative and said Я был страшен, it would completely change the meaning to "I was terrifying"!

Why is the preposition во used before сне instead of just в?

The preposition в often changes to во before words starting with certain consonant clusters, especially those beginning with с or з followed by another consonant (like сн in сне). This just makes it easier to pronounce. You will see the same phonetic rule in phrases like во вторник (on Tuesday). Also note that сне is the Prepositional case of сон (dream/sleep), which drops its о when its endings change.

What kind of word is наяву?