Ответ:
IV. 1. Had seen, I would have told
2. had left, would have left
3. are, will have
4. arrive, they will visit
5. go, you will not miss
V. 1. What is the official language of Australia?
2. Do you have a national cuisine?
3. Have you ever been in Sydney?
4. Is the weather always hot?
5. How do you care 'bout nature? What about government support in this field? (In Australia there are specific nature, is it true?)
Test 23.
I. 1 cattle.
2. mild.
3. cost.
4. state.
II. 1. When.
2. If.
3. If.
4. If.
5. When.
III. 1. On
2. In
3. Into
4. On
5. Of