Saheh Character and Mu'tal Character

in Arabic there are  Saheh Character (الحروف الصحيحة) and Mu'tal Character (الحروف المعتلة) :

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Mu'tal Character (الحروف المعتلة) are alef (ا); wawu (و) and Ya (ي) for example in this words:

1. قالَ
2. دعاَ
3. وجد
4. يقول
5. يدعو
6. يبس
7. يبيع
8. يشتري

Sahih Characer (الحروف الصحيحة) is words without Mu'tal Character, for example:

1. باب
2. ابن
3. عنب