English pronunciation || Sound like native speakers with this trick!

In the following items, each passage consists of six sentences. The first sentence (S_(1)) and the final sentence (S_(6)) are given in the beginning. The middle four sentences in each have been removed and jumbled up. These are labelled P, Q, and S. You are required to find out the proper sequence of the four sentences and mark accordingly on the Answer Sheet S_(1) : To a foreign learner, English pronunciation presents the greatest difficulty. S_(6) : But a knowledge of Phonetics will help a great deal in learning correct English pronunciation. P : Words are spelt in one way and pronounced in another. Q : For instance 'u' has different pronunciations in 'but', 'put', 'build' and 'bury'. R : The English language is notoriously un-phonetic. S : The same letters give different sounds in different words. The proper sequence should be :

Sound with intensity larger than 120 dB appears painful to a person. A small speaker delivers 2.0 W of audio output. How close can the person get to the speaker without hurting his ears ?