Questions & Answers about El libro verde es interesante.
Why is it verde and not 'verdo' to match the masculine word libro?
Do adjectives like verde and interesante ever change their endings?
Yes, they change to show plural! If you are talking about more than one thing, you just add an -s to the end. For example, 'the green books' would be los libros verdes and 'they are interesting' would be son interesantes.
Why does verde come after libro?
In Spanish, descriptive words (adjectives) like colors usually come right after the noun they describe. So instead of 'green book', the order is literally 'book green' (libro verde).