chews over, cogitates, considers, contemplates, debates, deliberates, entertains, eyes, kicks around, meditates, mulls (over), perpends, pores (over), questions, revolves, ruminates, studies, thinks (about or over), turns, weighs, wrestles (with)

muses (upon), reflects (on or upon), reminiscesanalyzes, explores, reviewsconcludes, reasonssecond-guesses, speculates (about)broods (about or over), dwells (on or upon), fixates (on or upon), frets (about or over), obsesses (about or over)believes, conceives, opinesabsorbs, assimilates, digests, drinks (in)

beats one's brains out (about), chews on, cudgels one's brains (about), looks at