Why does Andrea ask Zebra if he's "going to make gloomy drawings too"? From Zebra by Cham Potok

Because Zebra always seems to be sad and he always makes drawings and stories look the same.

Explanation:

Zebra is a very creative boy, but his face is melancholy and sad. This melancholy is his great inspiration as an artist, since their drawings and stories always have a sad tone. But Andrea doesn't seem to like this, and that's why she asks him, in the art class he's doing in the summer, if he will continue to draw such dark things.