my teacher marked these phrases as wrong but i don't know what about them is wrong:

1. je revelerais sans prevenir
2. j'ai vendu mes robes plus jolies

both of them need "un mot a ajouter"

Not sure but:

Je *me* revelerai sans... I will reveal *myself*... It's reflexive.

J'ai vendue mes robes les plus jolies. Can't explain it - it just sounds right.

Thank you for using the Jiskha Homework Help Forum. You have good help from Tony in that it could be reflexive OR have a direct-object involved. Somehow you need to "reveal/develop" SOMETHING.

#2 is no doubt saying "I sold my prettiest dresses." + J'ai vendu mes robes les plus jolies. (Just check the past participle.)

Mme

It seems that your teacher marked these phrases as wrong because they require some additional words to be grammatically correct.

1. "Je revelerais sans prevenir" should be "Je me revelerais sans prevenir" or "Je me revelerais sans prevenir a personne" depending on what you want to express. In French, reflexive verbs require the appropriate reflexive pronoun ("me" in this case) before the verb. Adding "a personne" specifies that you won't be revealing yourself to anyone.

2. "J'ai vendu mes robes plus jolies" is missing an article before "plus jolies." The correct phrase would be "J'ai vendu mes robes les plus jolies." In French, when comparing items, you need to use an article before the superlative ("les" in this case).

To avoid such errors in the future, it's helpful to review the specific grammar rules related to reflexive verbs and comparisons in French. Additionally, using language resources such as textbooks, online tutorials, or language learning apps can provide you with examples and exercises to practice and reinforce these concepts.