da- & wo-Komposita

The Unit 5 trap: with things, da- + preposition replaces the noun and wo- + preposition asks about it; before a vowel an -r- slips in. With people, the preposition stays with a pronoun:

• things: darauf, daran, darüber — questions: worauf, woran, worüber
• people: auf ihn, an sie — questions: auf wen, an wen