For each expression, identify the dominant contextual function of the relative phrase.
1. «الذي جاء معنا بالأمس عالم» — identification through yesterday's meeting, if the name is unknown.
2. «الذي حمى الضعفاء مكرَّم» — protection of the vulnerable suggests why honor is appropriate, with praise.
3. «الذي أهمل دروسه يشتكي من الرسوب» — the clause hints at an explanation for academic failure.
4. «الذي لا يعرف الطب يصف للناس دواء» — incompetence contrasted with prescribing medicine produces criticism or irony.
Core principle: grammar identifies the relative construction; rhetoric asks why it was selected for this audience and occasion. The next section turns to identification by demonstrative (الإشارة).