It helps people remember what once happened such as dreams, friendships and happiness.

它帮助人们记住曾经发生过的事情，如梦想、友谊和幸福。

youdao

People can hold on to things that once happened long, long after they happened.

人们可能对很久很久以前发生的事情仍旧耿耿于怀。

youdao

Once that happened, the themes of the opera presentations also started to change.

一旦这种情况发生了，歌剧表演的主题也会开始改变。

youdao

As has happened many times in the past, they are hoping that customers will flock back, once they get accustomed to the higher prices.

VOA: standard.2009.09.19

For example, the stock market crash of 1929 is repeatedly re-expected even though it only happened once; it's just prominent in our thinking.

929年股市崩盘,就被反复提及,尽管这只发生过一次,但是人们对它影响深刻

耶鲁公开课 - 金融市场课程节选

Everything that ever happened once, never happened until it happened.

FORBES: Will The High Dividend Yield Stock Bubble Burst?

That has happened once, and it happened last year, and Speaker Boehner was Speaker of the House.

WHITEHOUSE: Press Briefing by Press Secretary Jay Carney,

Any other self-respecting species would take the Darwinian hint and die once that happened.

BBC: Viewpoint: Just what is middle age?