Learn Turkish: Bu eski telgraf önemli bir mesaj için kullanıldı. - This old telegraph was used for an important message.

We start with the verb root kullan- (to use). Because it ends in a consonant, we add the passive suffix -ıl (following vowel harmony). Finally, we attach the simple past tense suffix -dı, resulting in kullanıldı (was used).

Is there a reason why kullan- takes the -ıl suffix instead of another passive ending?

Yes, it follows the standard rule taught in this lesson. Most verb roots ending in a consonant take -ıl (or -il, -ul, -ül). The main exception you will see are verbs ending in the letter 'l', which take -ın to avoid an awkward double 'l' sound (like bulmak becoming bulunmak). Since kullan- ends in 'n', it takes the regular -ıl.

Why is it önemli bir mesaj and not bir önemli mesaj?

In Turkish, when you have an adjective modifying a noun with the indefinite article bir (a/an), bir must go between the adjective and the noun. Saying bir önemli mesaj sounds unnatural, as it emphasizes 'one important message' as a number, rather than just meaning 'an important message'.

Why doesn't the noun phrase before için have any case endings?