c.o.
n. an odorless very poisonous gas that is a product of incomplete combustion of carbon 同义词：carbon monoxidecarbon monoxide gasCO
a hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition 同义词：cobaltCoatomic number 27
one who refuses to serve in the armed forces on grounds of conscience 同义词：conscientious objectorCO
a state in west central United States in the Rocky Mountains 同义词：ColoradoCentennial StateCO