1.Some of the ways people use music therapy are to reduce pain,or to stimulate brain activity.

여기서 to reduce 는 줄이는것 -명사적용법인가요
아니면 줄이기위해서 - 부사적 용법인가요

2.be able to prove
3.It has been known to contribute
여기서 to부정사는 무슨용법인가요?
답변부탁드려요~