Final answer:
A diptongo is a combination of two vowels within the same syllable. 'i' and 'u' can form diptongos with other vowels. The diptongos in the given words are 'ai', 'ei', 'ua', 'ie', 'ia', 'uo', 'oi', 'ua', 'ui', 'ue', 'ua', and 'ua'.
Step-by-step explanation:
A diptongo is a combination of two vowels within the same syllable. In Spanish, the vowels 'i' and 'u' can form diptongos with other vowels. Here are the diptongos in the given words:
Paisaje - 'ai'
Empeine - 'ei'
Ciudadana - 'ua'
Piedra - 'ie'
Viaje - 'ia'
Aurora - 'uo'
Boina - 'oi'
Cuatro - 'ua'
Rubio - 'ui'
Huevo - 'ue'
Europa - 'ua'
Cuidado - 'ua'