它的来源来自植物、动物或者其他物质，例如真菌类或者像酒等发酵产品。
It can be derived from plants, animals or other categories such as fungus or fermented products like alcohol.
畜牧业生产是利用在人类植物食物制造的剩余产品，像柑橘渣和甜菜渣，而无法以其他方式促进人类的食物供应。
Livestock production makes use of products left behind during the manufacture of human plant foods, like citrus pulp and sugar beet, which could not otherwise contribute to the human food supply.
尽管第一个长出木本的植物体积很小，但接下来的其他植物种群便能够因此迅速从木本结构优势种获利，仅仅几百万年的时间，其中一些具有木本的植物便进化得像现在的树一样了。
Although the first plants sporting wood were small, subsequent species quickly took advantage of wood's structural strength: in just a few million years, some had attained treelike stature.
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