Plain-Form + でしょう as “probably ___”
This grammar construct can be used with verbs, adjectives and nouns to express that something “probably VERB”, is “probably ADJECTIVE”, or is “probably NOUN” respectively. Whatever is used with this grammar pattern, it must be conjugated into its Plain-Form. For な-Adjectives and Nouns, the (です/だ) is not included between the respective な-Adjective or Noun and でしょう when this grammar pattern is used in the present tense; for other forms, such as the past-tense or Negative-Form, the respective conjugation of です is used (i.e. だった, じゃない). The word 多分（たぶん）, which itself translates to “probably,” is often used with this grammar pattern.
Kanojo no kaban wa arimasen. Tabun mou kaetta deshou.
(Her bag isn’t here. She probably already went home.)
Sono shiken wa tabun totemo muzukashii deshou.
(That test is probably really hard.)
Kare wa mainichi hamburger o taberu kara, tabun, suki deshou.
(He eats hamburgers every day, so he has to like them, right?)
Ano hito wa backpack ga aru kara, tabun, gakusei deshou.
(That person has a backpack so he’s probably a student.)