Learn Turkish: Pasaportun nerede? - Where is your passport?

By adding the 2nd person singular possessive suffix. Because pasaport ends in a consonant and its last vowel is an 'o', we use the suffix -un following the rules of 4-way vowel harmony. That gives us pasaportun (your passport).

Why doesn't the sentence say Senin pasaportun nerede?

You can include the pronoun senin (your) for emphasis, but it is completely optional. The suffix -un on pasaportun already clearly tells us that the passport belongs to you! Turkish speakers usually drop the pronoun unless they really want to stress the 'your'.

Where is the word for 'is' in this sentence?

In Turkish, the 'to be' verb (am/is/are) is often implied rather than written out, especially for 'he/she/it' subjects. Since 'your passport' acts as an 'it', no extra verb ending is needed. Pasaportun nerede? literally translates to 'Your passport where?', but means 'Where is your passport?'.

Why does the question word nerede end in -de?

The word nerede (where) is actually built using the locative suffix -de, which we learned earlier means 'in', 'on', or 'at'. It literally means 'at what place?'. Asking where a stationary object is located usually requires this suffix.