https://www.reuters.com/article/us-facebook-privacy-zuckerberg/second-day-of-u-s-congressional-hearings-awaits-facebook-ceo-zuckerberg-idUSKBN1HI1CJ >Facebook Inc Chief Executive Mark Zuckerberg returns to Capitol Hill on Wednesday for more questioning by lawmakers who have a rare chance to air grievances about the company directly to the head of the world's largest social media network.