The preposition di together with the preposition a belongs to the most used prepositions, we have already seen it very often.
di to add an infinitive
We have already seen in the chapter infinite verb forms that the mayority of the Italian verbs add an infinitive with di.
Mi chiede di aiutarlo.
He asked me to help him.
Ci consiglia di non andarci.
He recommends us not to go there.
di as a genitive
In this case di corresponds to the English preposition of.
La porta della casa è aperta.
The door of the house is open.
I prezzi degli alimenti salgono.
The prices of the food increases.
di to form composite words
Composite words are words compound of two other words. One possibility to connect them is the preposition di.
In general the relationship between the two words is not revealed, that something on must simply know or deduce from the context. The prepositions to be used are arbitrary.
Only the preposition da has a strong semantic value. It expresses the use of something.
