put in during, for or since (вставьте нужное слово).
1. we went with our experiments … a year. … this period of time it became clear that our approach had some disadvantages.
2. many problems were discussed … the conference and some of them … many hours. … the discussion different suggestions were made. the conference continued … a week.
3. biology made great progress … the second half of the xix century and … some time it was supposed that there is nothing much to be discovered.
4. man … thousands of years has been changing the world to suit his own purposes.
5. man has been changing the world … ancient times.
6. our team has been doing plasma research … three years.
7. he has been investigating the cell properties… he joined this laboratory.
8. i have been working at the effects of low temperatures on seeds… half a year.
9. we have been studying the theory of chromosome hereditary… last two years.
10. i have been gathering these data … last winter.
1. We went with our experiments FOR a year. DURING this period of time it became clear that our approach had some disadvantages.
2. Many problems were discussed SINCE the conference and some of them FOR many hours. DURING the discussion different suggestions were made. The conference continued FOR a week.
3. Biology made great progress DURING the second half of the XIX century and FOR some time it was supposed that there is nothing much to be discovered.
4. Man FOR thousands of years has been changing the world to suit his own purposes.
5. Man has been changing the world SINCE ancient times.
6. Our team has been doing plasma research FOR three years.
7. He has been investigating the cell properties SINCE he joined this laboratory.
8. I have been working at the effects of low temperatures on seeds FOR half a year.
9. We have been studying the theory of chromosome hereditary DURING last two years.
10. I have been gathering these data SINCE last winter.