past participle agreeing in number and gender

Question

Further to my last question about this, I clearly don't understand the rule, as these are wrong, can you explain please? :

Ils ________ pendant les vacances.They will have lost weight during the holidays.(HINT: Conjugate "mincir" in Le Futur Antérieur)auront minciauront mincisLearn and Discuss »
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7Cette sculpture est la plus belle ________ !This sculpture is the most beautiful you have ever seen!que tu aies jamais vueque tu aie jamais vu

Cécile Janty-Davies · Accepted Answer

Bonjour Chris,
Further to your prior question, please note that the agreement with the subject is only for verbs that conjugate with the auxiliary 'être' .
In the cases you quote, both the verbs mincir and voir take 'avoir' and the rules of agreement are with the object depending on its placement in the sentence.
Take a look at the following lesson to refresh your memory -
https://french.kwiziq.com/revision/grammar/special-cases-when-the-past-participle-agrees-in-number-and-gender-when-used-with-avoir-in-le-passe-compose-conversational-past
Hope this helps!