Since they use carbon dioxide for photosynthesis, they help keep atmospheric levels of the greenhouse gas in check.
(they; use; carbon dioxide for photosynthesis) (they; help; keep atmospheric levels of the greenhouse gas in check) Context(they help,List([50, 59))):(they; help keep; atmospheric levels of the greenhouse gas in check)
they help,List([50, 59))
they they they
use help help keep
carbon dioxide for photosynthesis
keep atmospheric levels of the greenhouse gas in check
atmospheric levels of the greenhouse gas in check