Sure, here are the sentences with the correct verb forms filled in:

31. When we **were** at school we all **studied** Latin.

32. When I **met** him, he **had been working** as a waiter for a year.

33. After he **finished** breakfast he **sat** down to write some letters.

34. She **has had** a hard life, but she's always smiling.

35. I think Jim **is** out of town.