But it is their ability to adapt and change that has helped them to survive and flourish in the 20th century.
(it; is; their ability to adapt and change that has helped them to survive and flourish in the 20th century) (them; to flourish; T:in the 20th century)
it them
is to flourish
their ability to adapt and change that has helped them to survive and flourish in the 20th century
T:in the 20th century