it's similar to portugues. in = em nel / nello = no nella = na negli = nos nelle = nas

http://www.oneworlditaliano.com/english/italian-grammar/articulated-prepositions-in-italian-2.htm in + il = nel We use this in the same cases as "in" when the noun which follows is masculine singular and starts with a consonant. Eg: Nel mare. / In the sea. in + la = nella We use this in the same cases as "in" when the noun which follows is feminine singular and starts with a consonant. Eg: Nella casa. / In the house. in + i = nei We use this in the same cases as "in" when the noun which follows is masculine plural and starts with a consonant. Eg: Nei casi. / In the cases. in + gli = negli We use this in the same cases as "in" when the noun which follows is masculine plural and starts with a vowel. Eg: Negli occhi. / In the eyes. in + le = nelle We use this in the same cases as "in" when the noun which follows is feminine plural and starts with a consonant. Eg: Nelle case. / In the houses. nell' We use this in the same cases as "nel" and "nella" when the noun which follows starts with a vowel. Eg: Nell' andito, nell' aria. / In the passage, in the air.