chewing over, cogitating, considering, contemplating, debating, deliberating, entertaining, eyeing(or eying), kicking around, meditating, mulling (over), perpending, pondering, poring (over), questioning, revolving, ruminating, studying, thinking (about or over), turning, weighing, wrestling (with)

musing (upon), reflecting (on or upon), reminiscinganalyzing, exploring, reviewingconcluding, reasoningsecond-guessing, speculating (about)brooding (about or over), dwelling (on or upon), fixating (on or upon), fretting (about or over), obsessing (about or over)believing, conceiving, opiningabsorbing, assimilating, digesting, drinking (in)

chewing on, cudgeling one's brains (about), looking at