In theory, you need molten iron in the core to generate one, but Mercury is so small, its core should have long since solidified.

理论上，你需要核心里的熔化铁来产生它，但是水星很小，它的核心凝固还要很久。

youdao

I have long since come to terms with my blindness.

我早就安于自己的失明了。

《新英汉大辞典》

Your growth plates have long since closed.

你的生长板早就闭合了。

youdao

(SAYING) On the southern coast - known as the Costa del Sol - block after block of apartments lie empty or half finished, many of them designed for foreign buyers who have long since abandoned the idea of investing in Spain.

VOA: standard.2010.06.24

These are long-term government bonds and I--now these are--since they're long-term, they have some uncertainty and variability to them.

这些是长期政府债券,由于它们是长期的，就存在不确定性和变化性。

耶鲁公开课 - 金融市场课程节选

It's been a really long time since I have personally followed basketball.

我个人看篮球真的已经很久了。

现场观看篮球赛 - SpeakingMax英语口语达人

But most of those young Reaganauts have long since taken the lobbying industry's dollar.

ECONOMIST: The only people who could stop a Bush second term

The days when companies used public markets as important sources of financing have long since passed.

CNN: Facebook needs to earn your trust

The hordes of Russian shoppers in search of consumer electronics have long since dwindled to a trickle.

ECONOMIST: Bizarre attractions