1. الطَّالِبُ مُجْتَهِدٌ: definite topic, indefinite predicate.
2. رَجُلٌ صَالِحٌ حَاضِرٌ: indefinite topic qualified by an adjective; «حَاضِرٌ» is the predicate.
3. فِي الْبَيْتِ ضَيْفٌ: fronted locative predicate, delayed indefinite topic.
The unifying idea is meaningful predication, not that every mubtadaʾ must physically be the first word.