Answer:
Eric et Ali sont beaux.
Il y a un nouveau eleve a lecole OU Il y a une nouvelle eleve a l'ecole.
Marielle a les yeux marrons.
Alice a une nouvelle voiture de sport.
Il y a des vieux livres a la bibliotheque.
Marcel a un vieux ordinateur.
Explanation:
m. = masculin
f. = feminin
s. = singulier
p. = pluriel
1) Since we can replace Eric and Ali into "ILS", we must know that it is m.p. And to transform beau (this word is m.s.), we would need to add an X at the end of the word.
*** Every adjective word that ends with EAU, EU, and AU; and we need to make it plural, you ALWAYS add an X at the end.
2) "Eleve" can be both masculin and feminin. Therefore, if no context is provided, always pretend that the subject is a boy. So, for safer answer, the answer will be (without context): Il y a un nouveau eleve a l'ecole.
3) Since yeux is the plural form of "Oeil" (eyes), you'd need to do a <em>Liaison</em> to marron. Les yeux is m.p. therefore applying it to marron, you's need an S.
4) Voiture is your subject in the sentence; and it is f.s. Therefore, apply nouveau and transform it into a feminin form, making it NOUVELLE
*** ___EAU is, most of the times, transformes to ___ELLE because of <em>Liasion of feminin form.</em>
<em />
5) In this sentence, your subject will be the LIVRES and not the bibliotheque, since we can take the words "a la biblio" out.
Livres is m.p. therefore, adding an X to vieux. The word stay the same. BUT, vieux is both singular and plural in masculin form. So don't get confused. Even if the word livres was in singular form (Livre), don't change the spelling of the word vieux.
***There may be a lot of exeptions like this one and you need to memorize them all, but once you get used to seeing them, you'll know when to add an S or X. Or maybe not add at all.
6) I explained everything up there, in number 5.
