Manganese is the most effective and most commonly used metal additive for improving combustion and suppressing smoke in both coal- and oil-burning applications.
(Manganese; is; the most effective and most commonly used metal additive for improving combustion and suppressing smoke in both coal- and oil-burning applications)
Manganese
is
the most effective and most commonly used metal additive for improving combustion and suppressing smoke in both coal- and oil-burning applications