Superlative adjectives are used used with preposition of?????? Thanks
Is it correct to say?
She is the best of these students.
She is the talles of her sisters.

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"She is the best of these students" is correct 
"She is the talles of her sisters" is not
Talles is not an English word :) If you mean "tallest" than that is correct :)

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Whoopsie! I meant to write "If you mean "tallest" THEN that is correct" :) haha finger-slip :)

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"She is the best of these students"  is correct 
"She is the talles of her sisters" is not
Talles is not an English word :) If you mean "tallest" than that is correct :)