La
Feminine singular before any consonant
L’
Feminine or masculine singular before any vowel
Le
Feminine plural
Il
Masculine singular before any consonant (except Z or S)
L’
Masculine or feminine singular before any vowel
Lo
Masculine singular before Z or S
Gli
Masculine plural before any vowel or before z or s plus a consonant.
I
Masculine plural before any consonant (except Z or S)