The milk is believed to be squirted into the calf's mouth via a tube formed by the calf's tongue and the mother's nipple. 我们认为乳汁是透过海豚宝宝的舌头与母亲乳头所形成的管状缝隙射入宝宝口中。
The model hypothesizes, for example, that a simple tubular feather preceded the evolution of barbs because barbs are created by the differentiation of the tube into barb ridges. 比如，我们的模型假设，简单的管状羽毛先于羽枝的演化，因为羽枝是由管子分化出羽枝脊才产生的。
美
