Los ojos de mi amigo son verde gris azules café

The answer for the question is:

- Los ojos de mi amigo son azules.

Explanation:

In Spanish, different to the English, the adjectives have plural form, then, when the substantive has the plural form, the adjective must has it too, in the sentence you have written: "My friend's eyes are...", with eyes that are a plural noun, next to must be assigned an adjective, in this case, the one adjective that is in plural form is "azules", the others are in singular form.

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