Answer the following questions to the text. 1. What quantities does physics measure? Are most of them interrelated? 2. How many systems of measurement are widely used nowadays? 3. All the nations of the world use the metric system, don't they? 4. What was used before the metric system? Did the earlier system have any drawbacks? 5. When was the idea of the decimal system realized? 6. What is the main unit of the metric system? How was it measured? 7. Were the units of area and volume defined as well? 8. Do shorter units have Greek or Latin prefixes? 9. What is a unit of mass? 10. Is there a difference between the metric system and the SI system? 11. When was the SI system introduced in the USSR? 12. What synonyms to the phrase 'metric system' can you find in the text?