The probable cause of the flooding was a blockage in the drains. It is probable that most medieval churches had paintings round the walls.
Advanced English Dictionary
adjective, noun +adjective likely to happen, to exist or to be true: the probable cause / explanation / outcome + highly / quite / most probable + It is probable that the disease has a genetic element. Compare: IMPROBABLE +noun ~ (for sth) (especially BrE) a person or an animal that is likely to win a race or to be chosen for a team: All four players are probables for the national team.
Collocation Dictionary adj
be, look, seem
extremely, highly, very | quite | equally
The two outcomes are equally probable.
Random quote: It is easier to live through someone else than to become complete yourself.: Betty Friedan