--ER=Take off the er and add the endings e, es, e, ons, ez, and ent.
--IR=Take off the ir and add is, is, it, issons, issez, issent.
--IR (2)=Remove the ir and one more letter for the first 3 forms. Add s, s, t. Add the letter back and add ons, ez, and ent.
--RE=Remove the re and add s, s, none, ons, ez, and ent.
