How sure: endings
A ladder of certainty from 'maybe' through 'should be' to 'no way', all on one base sentence about someone arriving.
kamo
polite kamo shiremasenmaybe / might
かも かもしれません
Marks something as possible but uncertain. It attaches to any plain clause, with no da after nouns (ame kamo).
sorosoro tsuku kamo
They might be here soon.
そろそろ着くかも
sorosoro tsuku kamo shiremasen
They may be arriving soon.
そろそろ着くかもしれません
kamo desu is common among younger coworkers but sounds a bit loose; with superiors or customers, use kamo shiremasen.
to omou
polite to omoimasuI think (that)
と思う とおもう と思います
Presents a statement as your own opinion or guess so it doesn't sound blunt. It attaches to the plain form, with da after nouns (ame da to omou).
sorosoro tsuku to omou
I think they'll be here soon.
そろそろ着くと思う
sorosoro tsuku to omoimasu
I think they'll be arriving soon.
そろそろ着くと思います
Use it for your own thoughts only; for someone else, say to omotteru. The casual variant is tte omou. For 'I don't think...', negate the clause: konai to omou (I don't think they'll come), not kuru to omowanai.
Learn alongside: kamo, n ja nai, hazu, wake naiLearn first: omou
n ja nai
polite n ja nai desu kaprobably / I'd say
んじゃない んじゃないですか
Gives a soft but fairly confident guess or opinion, either as a rising question or as a flat statement. After nouns, use na n ja nai.
sorosoro tsuku n ja nai?
They'll probably be here soon, no?
そろそろ着くんじゃない?
sorosoro tsuku n ja nai desu ka
I'd say they'll be here soon.
そろそろ着くんじゃないですか
A sharp, falling ...n ja nai! is a scolding 'don't!' (sawaru n ja nai!). Flat, it can also deny an explanation: asobi ni iku n ja nai = it's not that I'm going to play.
Learn alongside: kamo, to omou, hazu, wake naiLearn first: n da, ja nai?
hazu
polite hazu desushould be / supposed to
はず はずです
States what you expect on good grounds, such as a schedule, what someone said, or how things normally work. After nouns it is no hazu; after na-adjectives, na hazu.
sorosoro tsuku hazu
They should be here any minute.
そろそろ着くはず
sorosoro tsuku hazu desu
They should be arriving any minute.
そろそろ着くはずです
hazu ga nai means 'can't possibly'; hazu datta means 'was supposed to (but didn't)'. It is never advice: 'you should rest' is yasunda hou ga ii.
wake nai
polite wake nai desuno way (that...) / can't possibly
わけない わけないです
Flatly rules something out as impossible or absurd ('no way', 'as if'). On its own it makes the stock retort sonna wake nai (jan)! = no way / that can't be. It goes on any plain clause, often with jan or desho (wakaru wake nai jan = how would I know?), and nouns and na-adjectives take na before it (uso na wake nai, hima na wake nai).
mada tsuku wake nai yo
No way they'll be here yet.
まだ着くわけないよ
mada tsuku wake nai desu yo
There's no way they'll be here yet.
まだ着くわけないですよ
One ja softens it rather than flipping it: kirai na wake ja nai (kedo) = it's not that I hate it (but...). The same word is also an adjective meaning 'easy, no trouble': sonna no wake nai yo = that's nothing, one 'no' away from sonna wake nai yo = no way. Even in polite speech it flatly contradicts, so don't aim it at a superior's idea (say sore wa chotto... instead). The careful polite form is wake ga arimasen.
Learn alongside: kamo, to omou, n ja nai, hazuLearn first: hazu, -wake ja nai