The state will open hundreds of day care sites for children of those expected to keep working during the COVID-19 pandemic. Gov. Charlie Baker announced Saturday that more than 300 sites will open Monday, with more to follow later. The rest of the state’s child care facilities have been ordered to shut down to help prevent spread of the coronavirus. Baker said the drop-in sites are reserved for those who must report to work, including hospital workers and grocery store employees. Still, Baker said the sites should be used only “as a last resort.”