When Mark Zuckerberg testified before Congress last year, he was mocked for the sheer number of times he promised he'd "get back to" lawmakers about questions that he said he didn't know the answer to.
Zuckerberg, Tim Cook, Sundar Pichai and Jeff Bezos answered many questions directly during Wednesday's antitrust hearing in the House Judiciary antitrust subcommittee. But there were still plenty of questions that the CEOs pledged they'd get to later or declined to answer altogether.
Here's just a few of them.
'Isn't that anti-competitive?'
Rep. David Cicilline, the chairman of the House Judiciary antitrust subcommittee, came out swinging against Google during his first round of questioning, pressing Pichai over how Google treated restaurant review website Yelp.
Cicilline quoted documents in which Google threatened to delist Yelp entirely after Yelp complained the search giant was stealing its content.
"Isn't that anti-competitive?" Cicilline asked.
"Congressman, uh, when I run the company, I'm really focused on giving users what they want," Pichai said. "I'm happy to engage and understand the specifics, and answer your questions further."
'You were referring to companies like Instagram in that quote, weren't you?'
House Judiciary Committee Chairman Jerrold Nadler cited internal documents as he accused Facebook of acquiring Instagram in order to "neutralize a potential competitor." In a 2012 email obtained by the committee, Zuckerberg wrote, "One thing about startups is you can often acquire them."
"You were referring to companies like Instagram in that quote, weren't you?"
"Congressman, I don't have the exact document in front of me," Zuckerberg said, before launching into an explanation of Facebook's thinking about Instagram at the time.
The effects of GDPR
Rep. Kelly Armstrong, one of the few Republicans who focused on antitrust during questioning, pressed Pichai over how Google has been complying with privacy laws in Europe.
"I'm not familiar with the specifics of that question," Pichai said.
"You're not familiar with how you're complying with GDPR?" Armstrong asked.
Rep. Greg Steube launched into a lengthy monologue about his concerns that Google was not serving him conservative publication The Gateway Pundit.
"Was there anything done at Google … that has changed your approach to silencing conservative websites?" Steube asked.
"On the specific issue, I will have to look into it — I obviously wasn't aware of it," Pichai said.
"Can I expect a response from you in the next two weeks?" Steube asked.
"Congressman, we'll do our best to follow up and I'll engage with your office," Pichai pledged.
Rep. Mary Gay Scanlon cited internal documents that showed Amazon sought to crush Diapers.com after identifying them as a serious rival on its online retail platform.
"How much money was Amazon ultimately able to lose on this campaign to undermine Diapers.com?" Scanlon asked.
"Thank you for the question — I don't know the direct answer to your question, this is going back in time 10 or 11 years or so," Bezos said.
"Do you think this is an acceptable way to treat someone?"
Rep. Lucky McBath played audio from an Amazon seller who said Amazon started retaliating against her small family company "with no warning."
"After Amazon delisted this small business without any apparent reason or notice, she told us they sent more than 500 separate notifications to Amazon, including to you, Mr. Bezos, over the last year and received not a single meaningful response," McBath said. "Do you think this is an acceptable way to treat someone you described as both a partner and a customer?"
"I appreciate you showing me that anecdote," Bezos said, striking the conciliatory tone that he leaned on throughout the hearing. "I'd like to talk to her. It does not at all to me seem like the right way to treat her, and I'm surprised by that."
"I don't understand, but I would like to understand it better and with your permission, I'd like to get in touch with your office," Bezos said.
How Zuckerberg treated Evan Spiegel
Rep. Pramila Jayapal accused Zuckerberg of telling Snapchat founder Evan Spiegel that he was copying aspects of his app while attempting to buy Snapchat.
Jayapal asked, "Did you warn Evan Spiegel, the founder of Snapchat, that Facebook was in the process of cloning the features of his company while also attempting to buy Snapchat?"
"I don't remember those specific conversations," Zuckerberg said.
Will HBO Max be available on Amazon's Fire device?
Rep. Jamie Raskin said consumers are wondering when HBO Max will be available on Amazon's Fire device. "Is it fair to use your gatekeeper status role in the streaming device market to promote your position as a competitor in the video-streaming market with respect to content?" Raskin asked.
"I'm not with the details of those negotiations," Bezos said. "They're underway right now. I predict the companies will eventually come to an agreement."
"Are you using power in one domain into power in another domain where it doesn't belong?" Raskin asked.
"I think what I should do is offer to get you information," Bezos said. "I'll get it to your office."
What about PopSockets?
Rep. Hank Johnson described allegations from PopSockets, which has said it paid enormous sums of money in order for Amazon to deal with a scourge of counterfeits imitating its main product.
"If those are the facts and if someone somewhere inside Amazon said 'buy X dollars in ads and then we'll help you with your counterfeit problem,' that is unacceptable and we'll look into that and I'll get back to your office on that,'" Bezos said.
The allegations were described by PopSockets CEO David Barnett last year.
Music licensing on Twitch
When Armstrong began asking questions about Twitch, Amazon's video-streaming platform, it quickly became clear that Bezos did not feel prepared to answer any questions about the site or its music licensing practices.
"My understanding is Twitch allows users to stream music but does not license the music — is that correct?" Armstrong asked.
"I'm going to have to ask that I could get back to your office with an answer to that question," Bezos said. "I don't know."
The Alexa Fund
Rep. Joe Neguse asked Bezos to respond to allegations in a recent Wall Street Journal article, which found that Amazon launched competing products with startups after meeting with them about potentially investing in their businesses.
"Are you aware of those allegations?" Neguse asked.
"I don't know the specifics of that situation," Bezos said. "I would be happy to get back to your office with more information about that."