sentences: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past & a trilobite is a kind of water animal ->  if fossils of trilobites are found in a place, then that place used to be covered by water in the past  if fossils of trilobites are found in a place, then that place used to be covered by water in the past & fossils of trilobites are found in ohio & ohio is a kind of place -> ohio used to be covered by water in the past