d) many
b)the
d) an
18. Everybody agrees that ... happiness is very important in the life of people.
a) -
c) a
b) the
19. In the past people lived in ... harmony with the environment.
a) a
c) the
d) -
20. When they arrived ... the station, they rushed to the platform not to miss the train.
a)to
c)in
b) at
d) for
b) an​