cuando usar e en vez de y? cuando usar u en vez de o? write your expolanation in englsih

In Spanish, the conjunction "y" is used when the following word begins with any sound other than /i/ or /hi/. The conjunction "e" is used instead of "y" when the following word begins with the sounds /i/ or /hi/.

For example:
- "Gatos y perros" (cats and dogs)
- "Camarones e iguanas" (shrimp and iguanas)

Similarly, the conjunction "o" is used when the following word begins with any sound other than /o/ or /ho/. The conjunction "u" is used instead of "o" when the following word begins with the sounds /o/ or /ho/.

For example:
- "Perros o gatos" (dogs or cats)
- "Ojos u orejas" (eyes or ears)

These rules help to make the pronunciation of the language smoother and more natural.