Ответ:
1. A: Sandra has been teaching geography since she left university.
B: Yes, and she's a very good teacher, too.
2. A: How long have you known Helen?
B: We have been friends since we were children.
3. A: Who has been using my laptop?
B: I have. Is there a problem?
4. A: What are Mike and Joe doing?
B: They have been working in the garden for three hours.
5. A: You look exhausted.
B: Well, I have been cleaning the windows since 8 o'clock this morning.
6. A: Have you found your umbrella yet?
B: No, I have been looking for it for an hour now.
7. A: Have you got new neighbors?
B: Yes, they have just moved to the area.
8. A: Why is Mary upset?
B: She has lost her mobile phone.
9. A: Bill has opened a new café.
B: Really? Where is it?
10. A: I have always believed that exercise is good for you.
B: Of course, it's good to keep fit.
Объяснение: