The ancestors of plants were photosynthetic single-celled organisms that gave rise to plants presumably lacked true roots, stems, leaves, and complex reproductive structures such as flowers.

植物的祖先是进行光合作用的单细胞生物，由此产生的植物可能缺乏真正的根、茎、叶和复杂的生殖结构，如花朵。

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Nonetheless, there are indications that single-celled organisms can learn.

尽管如此，仍有迹象表明单细胞有机体可以学习。

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But they don't beat single-celled organisms that emerged about 3.4 billion years ago.

但是没有34亿年前出现的单细胞生物的历史久。

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His research began with fruit flies, but over the last two decades, his focus has been on parasitic protozoa, single-celled organisms that cause major diseases.

VOA: standard.2010.04.05

The single-celled organisms appeared to be harmless, though we were cautioned not to touch anything, to keep the windows shut, to wash our hands.

NEWYORKER: The Invasion from Outer Space

But even if single-celled organisms are all we can manage to discover in the foreseeable future, Darling is eloquent about the ways in which such findings are now changing how we think about our own existence.

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