This is done in an ad hoc fashion. It is not done in a systematic way.

VOA: standard.2009.08.31

I've been using the blackboard a little ad hoc here, but suppose I neaten things up here now and present this rectangle is let's say R RAM, the memory inside of your computer.

我在这里特别地使用这块黑板，假如我整理这些东西，把它们呈现,这个长方形，假如说就是内存，你电脑的内存。

哈佛公开课 - 计算机科学课程节选

Let me stop playing this since it will just go on ad nauseam as well. So what does this actually mean for you?

我们继续讲课,对你们来说这究竟意味着什么？

哈佛公开课 - 计算机科学课程节选

An independent expenditure arm of the Republican National Committee began running a new ad this weekend.

NPR: McCain, Obama Battle In Campaign Ads

And this is an issue where Mitt Romney is starring in an ad for this senator.

WHITEHOUSE: The White House

The latest digitally-driven marketing meme caught fire among the early adopter crowd late this Summer and is a hot topic of conversation at the New York ad fest this week.

FORBES: Advertising Week 2012: Get Ready For The Native Ad Wave