The reason we don't know about a lot of them is that they have vanished entirely.

我们之所以不太了解它们，是因为它们已经完全消失了。

youdao

And the reason we don't know about a lot of them is that they have vanished entirely.

我们不了解它们的原因是它们已经完全消失了。

youdao

We are obliged to them because some of these languages have since vanished,as the peoples who spoke them died out or became assimilated and lost their native languages.

我们感激他们，因为在此之后，由于说这些语言的部族或是消亡了，或是被同化而丧失了自己的本族语言，因而这些语言中有一部分已经消失了。

youdao

Any remaining doubt vanished as we rowed out towards the center of the lake.

WSJ: Cormorant Fishing in Yunnan Province, China

All the evils and miseries that we now suffer from have vanished.

NPR: Excerpt: 'All Art Is Propaganda'

The signs of a possible recovery that we saw in the spring of 2009 have all but vanished.

FORBES: Why Everybody Should Pray The Foreclosure Bans End