1. He knows quite a lot of English. He has been learning it for six years.2. I have been making cakes. That’s why my hands are all covered with flour.3. Her phone has been ringing for ten minutes. I wonder why she doesn’t answer it.4. We have walked ten kilometres.5. There is sawdust in your hair. – I’m not surprised. I have been cutting down a tree.6. She had been sleeping for 3 hours when we returned.7. They had been making their way through thick forest for some time before they came to a little house.8. By midnight they will have been riding for two hours.9. Nick wrote the letter yesterday and he hadn’t written it before I came.10. Mother wasn’t at home when I came. She had gone out half an hour before.