Single-unit FGD installations have occurred in as little as 20-21 months9, and multiple FGD systems have been installed within 36 months.
There many are installations of FGD that have occurred.
mnli hypothesis: There many are installations of FGD that have occurred. premise: Single-unit FGD installations have occurred in as little as 20-21 months9, and multiple FGD systems have been installed within 36 months.