Formal Address: Sie, Ihnen, Ihr

Use formal Sie with adults you don't know well, with customers, and with anyone you address as Herr or Frau + surname. It is the same for one person or several.

• Subject and accusative: Sie. Darf ich Sie etwas fragen? (May I ask you something?)
• Dative: Ihnen. Wie geht es Ihnen? (How are you?)
• Possessive 'your': Ihr, with the same endings as mein: Ihr Koffer, Ihre Nummer, Ihren Pass, mit Ihrem Mann, mit Ihrer Frau

Always write these forms with a capital letter, even in the middle of a sentence. With a small letter, sie means she, her, they or them, and ihr means you (plural), to her, her or their. The exercises cannot check capital letters, so pay attention to them yourself.