A Study to Evaluate the Safety and Effect of STC3141 Continuous Infusion in Subjects With Severe Corona Virus Disease 2019（COVID-19）Pneumonia

"To receive continuous infusion of STC3141 at rate 58.3mg/hr up to 3 days (72hours).~Also to receive appropriate standard of care."

"To receive continuous infusion of STC3141 at rate 87.5mg/hr up to 3 days (72hours).~Also to receive appropriate standard of care."