9. How old is your friend’s pet? 1. My friend’s pet is a wolf. — What colour is your friend’s pet? 2. His sister is five. — How old ______?

Во втором вопросе требуется спросить о возрасте сестры, поэтому используется конструкция How old is ...?

2. His sister is five. — How old is his sister?

Ответ: How old is his sister?