Wh- Question Words (Hard) — Which vs What, Whose

At advanced levels, wh- question words require understanding subtle differences that change meaning. The distinction between which and what depends on whether the set of options is defined: 'Which university did you apply to?' implies a known shortlist, while 'What university would you recommend?' keeps the options open. Similarly, 'whose' and 'who's' sound identical but serve completely different purposes — 'Whose idea was this?' asks about possession, while 'Who's coming tonight?' is short for 'who is.'

At B1-B2 level, you also need to handle wh- words in formal and academic contexts. 'To whom should I address this letter?' uses 'whom' as a formal object pronoun — in everyday English, most speakers say 'Who should I address this letter to?' instead. Another challenge is choosing between 'how come' (informal, statement word order: 'How come you're late?') and 'why' (standard, question word order: 'Why are you late?'). Both ask about reasons, but 'how come' is too informal for writing and examinations.