1. Light travels more quickly than sound.
2. He was here five minutes ago, but you were out.
3. The old man was thinking about his plan when he fell asleep.
4. Don’t speak to him: he is very busy, he is doing some urgent work.
5. When I entered the classroom, the teacher was writing words on the
blackboard and the pupils were copying them into their exercise-books.
6. This time next Tuesday I will be learning how to operate this machine.
7. What are you doing tomorrow evening? – I will be working on my research paper
the whole evening. I am afraid I won't be able to do it in time.