下列叙述中，哪一项与“小肠是最主要的吸收器官”这一功能无关（ ）
A．小肠长约5-6米，是消化道中最长的一段
B．小肠内表面有许多环形皱襞，内表面有许多小肠绒毛
C．小肠绒毛壁，毛细血管壁均是一层上皮细胞
D．黏膜上皮凹陷形成肠腺，分泌肠液
小肠在消化道内最长，长约5-6米；小肠壁的内表面有许多环形皱襞，皱襞上有许多绒毛状的突起，这种突起叫做小肠绒毛．由于环形皱襞和小肠绒毛的存在，使小肠的吸收面积大大增加，可达200平方米以上；小肠绒毛的壁很薄，只有一层上皮细胞构成，而且绒毛中有丰富的毛细血管和毛细淋巴管，这种结构特点有利于小肠吸收营养物质．所以小肠是吸收的主要器官．小肠内黏膜上皮凹陷形成肠腺，分泌肠液，肠液中有多种消化酶，可以对淀粉、脂肪、蛋白质进行消化，和小肠是消化的主要器官有关．
故选D．
通读下面短文，掌握其大意，然后在各小题所给四个选项中，选出一个最佳答案 Mr. Brown lives in a village. He has got a big family and a strong 1 . His farm is small and he is often 2 in winter. So he goes to the city and finds work there. Once he stayed there for about two months. When New Year was coming, he 3 home to see his wife and children. On his way home, something was wrong with his eyes. When he was knocking at the door, his dog came out and bit（咬） him. His wife hurried to drive 4 away. The next morning he went to see 5 . The doctor looked over his eyes carefully and gave him some medicine. Before he 6 , he told the doctor about his dog. When he heard this, the doctor began to 7 and said, “Maybe something is wrong with 8 eyes, too, I think.” When he got home, he told his wife about it. The woman said, “I 9 it’s true. If a thief comes into our house, it won’t see him and he’ll steal something here.” Mr. Brown thought his wife was 10 . He had to make his dog take his medicine instead.
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