Dual can be very tricky at times. The word (كِلا) in Arabic means ‘both’ in English. It is used mainly as part of an idaafa construction, either with a definite noun (كِلا الطالبان) ‘both students’ or a pronoun, e.g. (كِلاهما) ‘both of them’. Many people erroneously use (كِلا) with both masculine and feminine, without realizing that there is a feminine of the word which is (كِلتا); therefore, many people make mistakes in expressions like (كِلا اللغتين) ‘both languages’ and (كِلا الدولتين) ‘both countries’, when it should be (كِلتا اللغتين) and (كِلتا الدولتين).

In addition, when we mark the cases on these words, the final vowel is changes according to the case. i.e. we use (كِلا) and (كِلتا) in the (مرفوع) nominative case. When they are used in the (منصوب) accusative and (مجرور) genitive cases, the final vowel changes to (ي), e.g.

جاء كِلا الرجلان.

‘Both men came.”

زرت كِلتي الدولتين.

‘I visited both states.’

تكلمنا مع كِليهما.

‘We talked to both of them.’