Zuckerberg and Dorsey to testify about their social

Mark Zuckerberg, the chief executive of Facebook, and Jack Dorsey, Twitter’s chief, will appear before members of the Senate Judiciary Committee on Tuesday morning to defend actions by their companies to moderate speech. It is the second time in two months that the two C.E.O.s are testifying but this will probably have more fireworks than their last appearance as their companies took a central role during the recent election.