Rule reminder
SUBSTITUTION replaces an element with a pro-form (a grammatical substitute): nominal ('quello', 'tale'), verbal ('farlo', 'farcela'), or clausal ('lo', 'così'). ELLIPSIS omits a recoverable element entirely. Both avoid repetition and create cohesion, but substitution makes the relationship explicit via the substitute, while ellipsis leaves it implicit. Italian uses both strategies extensively.
Identify the substitution in: 'Ho bisogno di un libro su Dante. Puoi prestarmene uno?'