10.3.5.6 no congiuntivo if the subject it the same
The congiuntivo cannot be used if the subject of the main sentence is the same as the subject of the subordinate clause. If you speak French or Spanish you already know that.
English: I think that he has wone.
Spanish: Creo que ha ganado.
French: Je croit qu' il a gagné.
: Credo che abbia vinto.*
English: I think that I have wone.
Spanish: Creo haber ganado.
French: Je crois avoir gagné.
: Credo di avere vinto.
* The only thing we wonder about is the fact that the verb requieres the congiuntivo in Italian, but not in French or Spanish.
If the verb requires a preposition this preposition is to be used as well when adding the infinitive.
Credo che voi non abbiate capito.
I think that you didn' t understand.
Credo di non avere capito.
I think that I didn' t understand.
Ho fatto tutto affinchè tu possa studiare tranquillamente. I have done everything I could in order that you can study at ease.
Ho fatto tutto per poter studiare tranquillamente. I have done everything I could in order to study at ease.
Spero che lui sia già arrivato quando la festa comincerà.* I hope that he is here when the party begin.
Spero di essere già arrivato quando la festa comincerà. * I hope that I am here here when the party begin.
* Attention: If you speak Spanish. Yes, in Italian the future can be used after quando, the sentence is correct. What is a big mistake in Spanish, the use of the future after cuando to describe an action / event happening in the future is possible in Italian. In Spanish the congiuntivo is compulsory in this case, the use of the future an error. That' s not the case in Italian. In Italian the futuro is to be used in this case (if the subordinate clause introduced with cuando refers to something that will happen in the future.)