grammatically OK?

English as a Second Language English Vocabulary, Grammar and Idioms
#1
  1. The girl persisted to purchase that dress.
  2. The girl persisted purchasing that dress.
  3. The girl persisted in purchasing that dress.
    Are all these sentences grammatically OK?
#2

No.3 is the one acceptable and formal, for the word ‘persist’ takes the preposition ‘in’.

#3

No. 3 is the only one acceptable in any situation, not just formal situations.