"yazi yazmak" essentially includes an object "yazi" having a common meaning. So that, "yazi" is not used usually. If you want to emphasize what you write, the object might change into the words which refers to its particular meaning and you should use them. For example: Hikaye yazmak. Rapor yazmak. Makale yazmak. Mesaj yazmak. etc. In a discussion, If it is known what you are talking about, you dont need to repeat the object again. Such as: A: Dün, öğretmeninin istediği MAKALEYİ yazdın mı? B: Henüz yazmadım. Ama akşama kadar yazacağım. A: Yazdıktan sonra kontrol etmem için bana getirir misin? B: ........................................ In this dialouge, A indicates what B writes and uses the object "makale" once in the first sentence. In the following sentences, they do not use the object "makale" again. Because they know what they are talking about and only use the verb "yazmak" alone.