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