city-state overcrowding urban sprawl jet lag factor lighthouse metro index 1. an independent state consisting of a city and the area around it ………………….. 2. an underground train system ………………….. 3. a system that shows the level of prices and wages, etc. so that they can be compared with those of a previous date. ………………….. 4. the feeling of tiredness and confusion after you fly between places that have a time difference of several hours. ………………….. 5. a tower with a powerful flashing light that guides ships away from danger. ………………….. 6. a fact or situation that influences the result of something ………………….. 7. the situation when there are too many people or things in one place ………………….. 8. the spread of a city into the area surrounding it, often without planning ………………….. nhớ giải thích ạ!