A15. Unfortunately, Kate had to work part time (1) to fund her life at college (2), what prevented her (3) from joining in (4) with most of the evening activities on offer (5).

Ошибка в третьем фрагменте: what prevented her (3). Здесь неуместно вопросительное слово "what". Предложение требует относительного местоимения или союза, например, "which" или "that", чтобы связать две части предложения. Исправленное предложение: Unfortunately, Kate had to work part time (1) to fund her life at college (2), which prevented her (3) from joining in (4) with most of the evening activities on offer (5).