Поставить в правильной форме слово указанное в скобках:

Open brackets and use the correct tense.
1. General relativity (be) a theory of great significance.
2. The students estimated how much time the task (taken).
3. The weather report says it (rain) tomorrow.
4. Temperatures (rise) as a result of global warming.
5. For years, environmentalists (encourage) computer users to recycle their old computers instead of simply throwing them out.
6. The cost of living (rise) very fast. Every year things are more expensive.
7. Over the last few years USB Flash Drives (become) a must-have item for computer users everywhere.
8. In the past few months, several European countries and Japan (pass) laws declaring waste (such as old computer hardware) cannot be exported.
9. Development of flexibe electronics recently (focus) on organic molecules.
10. Gregory is a vegetarian. He (not/eat) meat.
11. We (drive) home in the middle of the night when we (see) a flashing light.
12. The weather (be) awful in the past few days.
13. I’m tired. We (walk) 10 miles.
14. In recent months, environmentalists from developed nations (visit) these recycling centers.
15. When I (walk) through Bologna I (think) about the wonderful times I (spend) there as a student.
16. The vast majority of portable systems (use) batteries that contain poisonous heavy metals, such as cadmium.
17. We had a long meeting, by the end of which she (accept) our proposal.
18. I work part-time in a student counselling centre, where I (be) a volunteer for the past three years.
19. Language learning strategies (become) a popular area of research.
20. The Aztec people (believe) that human sacrifice was essential.