在消化道内,下列各项不能被人体直接吸收的营养成分是( )
①蛋白质 ②葡萄糖 ③麦芽糖 ④脂肪 ⑤淀粉 ⑥氨基酸 ⑦水 ⑧初步消化的蛋白质 ⑨维生素 ⑩无机盐.
A:②⑥⑦⑨⑩
B:③⑥⑦⑧⑨⑩
C:①④⑤⑦⑨⑩
D:①③④⑤⑧
Many students in our school _______ the old and they usually offer their seats to them on buses.