Learn English Vocabulary. Idioms. Different Ways to Say "I'm busy" #shorts

Some parts of the sentence have been jumbled up. You are required to rearrange these parts which are labelled P,Q,R and S to produce the correct sentence . Choose the proper sequence and mark in accordingly. Based firmly on current lexical and learning theory ("not only to present and to explain words")/(P) , ("English Vocabulary in Use aims")/(Q) , (" and to help them work out the rules themselves")/(R ) , ("but also to show students how to use them")/(S) . The correct sequence should be