Where Bucharest now stands, there once was a large, dense forest.

现在的布加勒斯特所在地曾经是一片茂密的大森林。

《柯林斯英汉双解大词典》

National chains that once ignored Harlem now anticipate yuppie money and want pieces of this prime Manhattan real estate.

曾经对哈莱姆区视而不见的全国性连锁企业，现在期待着雅皮士的钱，还想要占据曼哈顿的黄金地产。

youdao

Some birds which were once a common sight are now becoming rare.

有些曾经随处可见的鸟类现在日益稀少。

《牛津词典》

But now it seems that T.rex may not have been as fierce as scientists once believed.

VOA: special.2009.09.01

I want to show you how easy it is to change the code. But, notice, once I've added this I actually have a problem. This is now an under-constrained problem. I have more unknowns than I have equations.

我加上这个条件后,我马上面临一个问题了,这就是现在是一个非约束性问题了,我的未知数比方程数多,你从代数中可以知道。

麻省理工公开课 - 计算机科学及编程导论课程节选

.. Now, once you have more than three-- more than two assets-- it might be possible to get points inside the frontier.

现在，一旦你有超过三种-,超过两种资产-,就有可能取到边界里面的点。

耶鲁公开课 - 金融市场课程节选

You've been through it once now, and you understand how you've got to carry yourself.

WSJ: Rising star Stepan eyes playoff run for Rangers

The Navy insists that it supports the plan of record for the Lockheed Martin plane, but it has already restructured the program once and now is studying whether the number of F-35s in carrier air wings should be cut due to cost constraints.

FORBES: Outcome Of Three Programs Will Drive Defense Sector Consolidation

So if you go once a week now, you're only going once every two weeks.

WHITEHOUSE: Press Briefing by Deputy Press Secretary Josh Earnest