﴿أَنَّىٰ يَكُونُ لِي غُلَامٌ وَقَدْ بَلَغَنِيَ الْكِبَرُ﴾
How can I have a son when old age has overtaken me? (Āl ʿImrān 3:40)
The expression wa-qad balaghaniya al-kibaru is a verbal clause with a past-tense verb. It describes the speaker's condition at the time of the question and explains why the prospect seems remarkable. Here wāw expresses an attendant circumstance, while qad reinforces the already-realized nature of reaching old age.