(science fiction) time travel (Requires a device like a time machine and that the traveler is status quo.)

possibility; probability; likelihood

possible / feasible

possibility, good chance / feasibility

sex, gender / (grammar) gender

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

to research, to study

a piece of research, a study, investigation

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend