kāna + Present and qad

كان + present tense describes a past habit or an ongoing past action, like English used to or was …ing. Conjugate كان for the person, then add the present-tense verb for the same person:

• كنتُ ألعب (I used to play), كانت تطبخ (she used to cook), كنا نسكن (we used to live), كانوا يعملون (they used to work).
• When كان comes before a noun subject it stays singular, but the second verb agrees fully: كان الأطفال ينامون (the children were sleeping).

قد changes its meaning with the tense after it:

• قد / لقد + past = has already, did indeed: لقد وصل القطار (the train has arrived).
• قد + present = may, might: قد ينزل المطر غدا (it may rain tomorrow).

Words like أمس or قبل دقيقة call for the past, غدا or القادم for the present. لقد is only used with the past.