In contrast, if we talk about a double bond, what we're now talking about is having both a sigma bond and also one pi bond. And I apologize, I intended to set this up right before class, but that didn't happen today.

相反，如果我们讨论一个双键，我们现在讨论的是,一个sigma键和π键，抱歉，我应该在课前就把这个装好的，今天没装好。

麻省理工公开课 - 化学原理课程节选

As soon as we saw the first Tweet from Mr. Smith, we contacted him personally to apologize for his experience and to address his concerns on both Twitter and with a personal phone call.

FORBES: The Kevin Smith - Southwest Airlines tweet battle (And why you should be on Twitter too)