Ответ:
1.
1. Past Perfect
We hadn't already cleared up all the points for the talks by 11 o'clock.
Had we already cleared up all the points for the talks by 11 o'clock?
Мы прояснили все пункты для разговоров (бесед) к 11 часам.
2. Present Simple
My friend doesn't work at the State Tax Inspection.
Does your friend work at the State Tax Inspection?
Мой друг работает в государственной налоговой инспекции.
3. Past Continuous
They weren't discussing business plans from 2 to 4 o'clock.
Were they discussing business plans from 2 to 4 o'clock?
Они обсуждали бизнес планы с 2 до 4 часов.
4. Present Continuous
He isn't holding a meeting now.
Is he holding a meeting now?
Он ждёт встречу сейчас.
5. Present Perfect
Boris hasn't been in business since last March.
Has Boris been in business since last March?
Борис в бизнесе с прошлого марта.
6. Past Simple
We didn't settle ail problems.
Did we settle ail problems?
Мы решили сложные проблемы.
2.
1. What we want to do with a private company?
2. What did our firm make in this business?
3. What are we learning?
4. When have we taken the customer's representatives to the design institute?
3.
1. Ann speaks English.
2. We will sing the contract by next Saturday.
3. Our firm has taken part in the talks at present.
4. We had received a lot of goods by that time.