I bet (you) can be used in an informal style to mean ‘I think it’s probable that‘. That is usually dropped.
- I bet (you) she’s not at home. (More natural than I bet (you) that she’s not at home.)
I’ll bet … is also possible.
- I’ll bet you she’s not at home.
After I bet (you), we often use the present tense to refer to the future.
- I bet (you) they don’t come this evening. (OR I bet (you) they won’t come … )
- I bet (you) the Conservatives (will) lose.
When bet is used to talk about real bets, it can be followed by two objects: the person with whom the bet is made, and the money or thing that is bet.
- I bet you £5 it doesn’t rain this week.
- My father bet my mother dinner at the Ritz that she would marry him. He won, but she never bought him the dinner.
Bet is irregular (bet – bet – bet).