One morning Mr. Green is driving 1the country and2a small bookshop. When he sees an old man3the side of the road, he stops his car and says to the old man, "I want 4to the Sun Bookshop. Do you know it?" "Yes, "the old man answers, "I 5 you the way. "He6Mr. Green's car, and they drive about twelve miles.7they come to a small house, the old man says, "Stop here. "Mr. Green stops and 8the house. "But this isn't a bookshop, "he says to the old man. "Right, "the old man answers, "This is my house. And I'll show you the way 9the bookshop. Turn around and go back nine miles10you'll see the bookshop. "

对下列代数式作出解释，其中不正确的是（　　）