If you need to make up a sentence so that it should have a parallel structure it means that the second part of the sentence must have the same pattern of words. It is needed to emphasize that both parts of the sentence have the same importance. Alice worked hard to ensure that her presentation was creativel, effective and persuasive. (the same structure - adjectives) The teachers like John because he never came late to the classes, always got his homework in time and was very polite to teachers. (the same form of representing qualities).
