Hi can someone help me with these spanish questions, also the ones I did I wanna know if Im correct because Im confused

Fill the blank with a la, a los, a las, or al. los alumnos

1. completa la oración con la voz pasiva. the book was written by cervantes. el libro por cervantes 2. completa la oración con la voz pasiva con ser. the tall building was designed by the architect. el edificio alto por el arquitecto. 3. completa la oración con la voz pasiva con ser. the cookies were eaten by the children. las galletas por los niños. 4. completa la oración con la voz pasiva con se. the cake was eaten. la torta. 5. completa la oración con la voz pasiva con se. used cars for sale. carros usados.

Which in spanish an example of: 1) a comparison between two unlike things, and 2) something that you consider the best. when creating your two sentences make sure to use the following expressions: mejor que, peor que, el/la mejor, el/la peor