They are called fossil fuels because they have been formed over long periods of time from ancient organic matter.
(They; are called; fossil fuels; because they have been formed over long periods of time from ancient organic matter) (they; have been formed; T:over long periods of time from ancient organic matter)
They they
are called have been formed
fossil fuels because they have been formed over long periods of time from ancient organic matter
T:over long periods of time from ancient organic matter