[求助]请教 99。10 一道语法题

40。Collagen, a strong rubbery protein, supports the ear flaps and the tip of nose in humans.

Key: D . Why?

Why not C , of nose. Nose is countable noun while it has not articles or pl. form.

Thank you for your attention.

非常好的帖子，打消了我所有的疑虑，这种执著的精神真叫人感动。非常感谢likui GG.