If you say that something is probably the case, you think that it is likely to be the case, although you are not sure.
The White House probably won't make this plan public until July.
白宫可能要到7月份才会公布这项计划。
Van Gogh is probably the best-known painter in the world.
凡高可能是世界上最知名的画家。
You can use probably when you want to make your opinion sound less forceful or definite, so that you do not offend people.
What would he think of their story? He'd probably think she and Lenny were both crazy!
他会怎么看他们的故事呢?他可能会认为她和伦尼都疯了!