? He must have left by now. (I'm sure he left.) They are late. They may/might have lost their way. (It was possible.) He can't have eaten the whole cake. (I'm sure he didn't do it.) You should have booked a table. (but you didn't.) 1 I'm sure she didn't do the shopping. (CAN'T) 2 I'm sure Mum bought us some doughnuts. (MUST) 3 They wanted to buy a cake for his birthday but they didn't. (SHOULD) 4 It was possible that she had left the invitation at home. (MAY) 5 I'm sure the decorations cost a lot. (MUST) 6 He isn't feeling well; he ate too many sweets. (SHOULDN'T)