all the people who live in a particular area, city or country; the total number of people who live there
population
self-driving
driveless
to be less and less difficult to do or understand
get easier
a source of power, such as fuel, used for driving machines, providing heat, etc.
energy
to become larger in number, amount or degree
increase/ go up/ rise
to be more and more difficult to do or understand
get harder
to make something better, or to become better
improve
to become less or go down to a lower level
decrease/ go down/ fall
to make (something) smaller or less in size, amount or price
reduce
to become more unpleasant, bad or severe
get worse
the process of making air, water, soil, etc. dirty
pollution