The key answer of exercise 5

a)

1. present perfect simple
2. present perfect simple
3. present continuous
4. past continuous
5. past perfect simple
6. past perfect simple
7. present perfect continuous
8. present perfect simple
9. past perfect simple
10. future continuous

b)

1. continuous → 1, 2, 4, 7; perfect → 1, 3, 4, 5, 6
2. existing tenses → past / present / future continuous, past / present / future perfect continuous. In Ex 5A → past / present / future continuous, present perfect continuous. The speaker sees the action as ongoing (in relation to the point in time referred to) and as having limited duration.
3. existing tenses → past / present / future perfect; past / present / future perfect continuous. In Ex 5A → present / past perfect simple, present perfect continuous. The action happens before a particular point in time and is relevant to that point in time.

c)

1. 5, 6, 9
2. 1, 2, 7, 8
3. 10
4. 4
5. 3
6. 7