How to differenciate the long vowels from the actual letters in arabic?

Question

I'm learning beginner in arabic and I can't find a proper grammar rule to figure it out.

There is a lot of lessons on long vowels but they are totally disjointed from the question "How to differenciate them from normal letters ?"

The perfect example to illustrate my question is "كيف نقول؟" The first time I read it on the front page of a book, I read "kif naqul ?". For me "كي" was the long vowel i. A native speaker corrected me by telling me it was "kayfa" but was not able to explain to me how to know without knowing the word.

For the same reason, why is it قو = qu and not قو = qewe because و is the waw letter.

Is there a grammar rule I can stick to, to recognize when it is a long vowel or a normal letter ? Or do I must just learn the word to know what is the pronunciation ?

Answer 1

To be sure, you need to see the word with ħarakat: optional marks around the letters that indicate the vowels.

Seeing كيف on its own (and with no background knowledge), all you know is KYF—it could be kayfa, or kīfu, or kuyaffi, and so on. So most textbooks for beginners will write it as كَيْفَ, with the ħarakat, which tells you unambiguously that it's kayfa.

(Why don't experienced Arabic-speakers get confused? The same reason yu cn rd Englsh wrds wth all the intrnl vwls rmvd: they know that kayfa is a real word, and kuyaffi isn't. Even when the letters could spell multiple words, context generally makes it clear which one is meant.)

So for now, I'd recommend finding a textbook with ħarakat. Once you have more experience with the language, it'll become easier to figure out whether ي and و are being used as vowels or consonants.