AD

abbr. (advertisement的缩写)广告
n. (缩)广告

I got four replies to my ad about the bicycle for sale.

已经收到了四份对我出售自行车广告的回信。

Fished all day without a bite; an ad that got a few bites but no final sales.

一整天没半条鱼上钩；这则广告吸引了一些人上钩，但最后还是没有卖出东西