The key answer of exercise 7

1

1. (refund / amount is more important than the person refunding)
2. (we don’t know who the doer is, and it’s unimportant)
3. (the doer could be anyone and we’re more interested in the acceptability of the dollars)
4. (who or what caught him out in each case is unimportant)

2

be (in different forms) + past participle 

3

Students’ answers (you might want to prompt some ideas – e.g. present tense?)