Ответ:

22. Tim looks pale, so he may have been ill recently.

23. Helen is absent from the lesson, so she could have caught a cold.

24. Mary's hairstyle is great, so she must have found an excellent hairdresser.

25. Zoe has a sun tan, so she must have been in Spain recently.

26. Sam is happy, so he may have passed his exams last week.

27. Tom isn't here, so he can't have gotten my message.

28. Sue looks depressed, so she might have had an argument with her boyfriend.

29. Andy is tired, so he could have been at that party last night.