Unit 4. The paper-bag mystery. One day Billy and his mother go for a ride on a bus. They want to visit Grandmother. There are many people in the bus. Billy looks at the people. A man has a book. A woman has a lot of things in her hands: a big bag, three boxes, two books and some red flowers. Suddenly Billy sees an old lady. She has a white paper-bag in her hands. Billy is surprised. This paper-bag dances. "What can it be?" thinks Billy. It is a big mystery. "Who? Why? What?" thinks Billy. Suddenly the bus stops and Billy hears a very loud "Mew!" Then he sees two little black ears, and a little pink nose, and two green eyes. "Oh, it's a ... kitten!" says Billy, and he laughs.