perhaps 也许;是也许如此、也许不如此的意思,大体和possibly同义
probably 大概;肯定的成分较大,是most likely的意思
maybe 或许;比perhaps普通,但不够庄重
Perhaps the letter will come today.
或许那封信今天能到。
It will probably rain.
天很可能要下雨了。
It's clouding up. Maybe it'll rain this afternoon.
天阴了。今天下午也许有雨。