1. I was able to understand my sister very well since she went to school (I am using PAST in either parts of the sentence, though I think PRESENT is technically also possible in the first part)
2. I would like to be able to swim well
3. I don't think I will be able to come to the party on Saturday
4. She has never been able to play the piano
5. He enjoys being able to go to the theatre every week

I think that's it .... Natives, correct me if I am wrong.