Question

1.The scientists (to discuss) this problem already.2.Scientists (to develop) air pollution dispersion models to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle exhausts and industrial flue gas stack emissions

Answer 1

1.The scientists has already discussed this problem. 2.Scientists are developing air pollution dispersion models to evaluate the concentration of a pollutant at a receptor or the impact on overall air quality from vehicle exhausts and industrial flue gas stack emissions