Almost five months after two major health care systems with campuses in Keene and Peterborough announced their intention to become one, people can comment on the plans at a local listening session. The session is slated for Thursday from 6 to 7:30 p.m. at Bass Hall in the Monadnock Center for History and Culture, 19 Grove St., Peterborough. It comes after three similar meetings last month, in Manchester, Wolfeboro and Lebanon.