There are five kingdoms: animals, plants, fungi, chromists—including one-celled plants such as diatoms—and protozoa, or one-celled organisms.

归有五个界：动物界、植物界、真菌界、茸鞭生物界——包括单细胞植物，如硅藻——和原生动物界，或单细胞生物体。

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In short, all living things are developments from these one-celled organisms. They have developed step by step through change upon change from these first, simple, living things.

简而言之，所有的生物都是这些单细胞生物体的后代，它们是从这些最早的、简单的生物体经过逐步演变进化而来的。

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At the time, Venter was trying to accelerate the process of sequencing whole genomes, first one-celled organisms, but ultimately gearing up to take on the decoding of the human genome.

FORBES: Venter and the Vatican

We looked up at the sky, we waited for more news already we were hearing reports that the substance was composed of one-celled organisms and through it all we could sense the swell of our disappointment.

NEWYORKER: The Invasion from Outer Space