Complex sentence: A comprehensive school is a secondary school that is a state school and does not select its intake on the basis of academic achievement or aptitude, in contrast to the selective school system, where admission is restricted on the basis of selection criteria.
Split into simpler sentences: A comprehensive school is a secondary school that is a state school and does not select its intake on the basis of academic achievement or aptitude. In contrast to the selective school system, where admission is restricted on the basis of selection criteria.