Questions & Answers about Bu kitabı okuyorum çünkü gerekli.
Does çünkü change the word order of the sentence?
No, çünkü (because) is very straightforward. It simply sits between two complete thoughts, just like in English. You have 'I am reading this book' (bu kitabı okuyorum) and 'it is necessary' (gerekli), joined together by çünkü.
Why is the word for book spelled kitabı here instead of kitap?
Two things happen here. First, because you are reading a specific book ('this book'), kitap takes the specific direct object suffix -ı. Second, when a vowel suffix is added to a word ending in p, the p softens to a b to make it easier to pronounce. So, kitap + ı becomes kitabı.
Where are the words for 'it is' before gerekli?
In Turkish, 'it' is usually dropped when the context is clear. Also, for the present tense 'is' (for 'he/she/it'), there is no suffix at all. So the single word gerekli (necessary) works perfectly as a full sentence meaning 'it is necessary'.
Why doesn't the verb okuyorum have a buffer vowel before -yor?
The root of the verb is oku (to read). Because it already ends in the vowel u, the present continuous suffix -yor can attach directly without needing an extra buffer vowel to separate consonants. Then you just add -um for 'I'.