Выберите правильный вариант ответа.
1. What … American public schools teach?
a) are
b) is
c) do
2. Now she … difficulty in putting facts in order.
a) is havingb) has been having
c) had
3. Recently BBC experts … a new system that lets the deaf understand television programmes.
a) have invented
b) invented
c) invent
4. You are a good football-player. Since when … you … football?
a) have … been playing
b) did play
c) had … been playing
5. … you … the ancient stone carvings at the museum last week?
a) have … seen
b) did … see
c) had … seen