You have a tube, a transparent--a tube--a hollow tube, and at the top of the tube you throw a ball through so it whips through the tube and it comes out.
用一根管子,一根透明中空的管子,从管子最上面,你丢进去一个小球,小球迅速穿过管子,飞出来
This tube, this hollow tube, which food passes through is made up of many, many epithelial cells which directly abut one another and would be a flat sheet except that it's rolled up into a tube.
这个管道,这个中空的管道,食物可以穿行其中,而它就是由许多许多上皮细胞构成的,上皮细胞一个连着一个,形成了一个平坦的细胞层,但实际上它们还在肠管中卷成管状
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