1 There is a chance that he will arrive tonight.He may arrive tonight. 2 I'm sure Gary hasn't flown to Detroit;the weather's too bad.Gary can't have flown to Detroit;the weather's too bad.
3 He's soaking wet-I'm sure he been walking in the rain.He's soaking wet-he must have been walking in the rain. 4 A drought is possible here, even in the winter.There may be a drought here, even in the winter. 5 I'm sure he didn't catch the 8 o'clock plane.He must have missed the 8 o'clock plane.