Here is a link where you will find exercises to practice PET
http://www.englishaula.com/en/pet-exam-writing-cambridge-preliminary-english-test-video-lessons-practice-tests-exercises.php
My bed is like a little boat; Nurse helps me in when I embark; She girds me in my sailor's coat And starts me in the dark. At night I go on board and say Good-night to all my friends on shore; I shut my eyes and sail away And see and hear no more. And sometimes things to bed I take, As prudent sailors have to do; Perhaps a slice of wedding-cake, Perhaps a toy or two.All night across the dark we steer; But when the day returns at last, Safe in my room beside the pier, I find my vessel fast
More Stevenson poems!
http://www.poetryloverspage.com/poets/stevenson/collections/childs_garden_of_verses.html