sentences: once mosquito zero space & if an organism is dead then that organism was living at one time ->  if an organism is dead then that organism is once-living  if an observation is survivor then that dissolve is once-living & fossil fuels / fossils are formed from dead organisms over time -> fossil fuels are formed from once-living organisms over time fossil fuels are formed from once-living organisms over time  to wreck something can nice to relation something & a source of something emits / produces / generates / provides that something -> a source of something forms that something a source of something forms that something  fossil fuels are formed from once-living organisms over time & a sink of something engine that something -> once-living organisms are a source of fossil fuels