1) attend,go,visit,enter 2)coprevensive,primary,higher,compulsory3) fail,pass,enter,take 4)optional,private,public,state5)college,gymnasium,lyceum,kindergarten 6)university,college,academy,conversatory,7)gcse,a level,entrance,further

                                                             odd words
1) attend, go, visit.                                 (enter)
 2) coprevensive, primary, higher.       (compulsory)
 3) fail, pass, take.                                 (enter)
 4) private, public, state                         (optional)
 5) college, gymnasium, lyceum.           (kindergarten)
 6) university, academy, conversatory. (college)
 7) GCSE, A level, entrance.                 (further)