They died off a long time ago.

他们很久以前就灭绝了。

It was likely only a few hundred people and they may have died off.

他说，当时可能只有几百人，他们可能已经灭绝了。

So it begs the question, what would happen if all of the bees died off?

这就引出了一个问题，如果所有的蜜蜂都灭绝了，会发生什么？

That inability to reproduce spread across the mosquitoes and the entire population died off within eleven generations.

这种无法繁殖的情况会在蚊子之间传播，这样，整个蚊子群体不出11代就会悉数灭亡。

It is not clear how many early humans died off during this cold period, the researchers said.

研究人员说，目前还不清楚有多少早期人类在这段寒冷时期死亡。

Over time, giraffes with longer necks flourished eating up high, and giraffes with shorter necks eventually died off.

随着时间的推移，脖子较长的长颈鹿在高处觅食，脖子较短的长颈鹿最终死亡。

At least 20 African migrants trying to reach Europe by boat have died off the coast of Central Tunisia.

至少20名试图乘船抵达欧洲的非洲移民在突尼斯中部沿海死亡。

Other scientists wonder if it is even a good idea to attempt to recreate species that have died off.

其他科学家想知道，试图复活已经灭绝的物种是否是一个好主意。

Thirty-six of those species are close to dying off completely.

其中有36种相继走向完全灭绝。

This hypoxia also causes the parasympathetic nerve fibers to die off.

这种缺氧还会导致副交感神经纤维死亡。

Supporters of populism will become disillusioned, or will simply die off.

民粹主义的信众会幻灭或离世。

Still, most cell lines eventually die off, especially outside the human body.

但是，一般的细胞系，特别是在人体外的 最终会死去。

Eventually the enamel-building cell dies off, leaving a long crystalline rod behind.

最终造釉细胞死亡，留下了长长的透明结晶体。

As with other kinds of variant, most will die off relatively quickly.

和其他种类的变体一样，大多数变体会相对较快地消亡。

The living matter within the cell dies off, leaving behind only the cellulose.

细胞死亡，只留下纤维素。

It will now continue to fall for decades, as larger generations die off.

现在，随着人数更多的几代人死去，韩国人口将继续下降数十年。

Coral infected with it die off at a rate of 66 to 100 percent.

感染了这种疾病的珊瑚的死亡率为66%到100%。

Some whale species are dying off because climate change has affected their supply of food.

由于气候变化影响了鲸类的食物供应，一些鲸类正在灭绝。

Fewer stars will be born, and the ones already born will start to die off.

诞生的恒星会变得更少，而那些已经诞生的恒星会开始消亡。

For many years, scientists have worked to bring the pelicans back from totally dying off.

多年来，科学家一直在努力使鹈鹕免于灭绝。