阅读短文，判断对错。

A little boy goes into a shop. The salesgirl is happy to ask him, "Can I help you?" "My mum asks me to buy some clothes. How much are the socks?" he asks. "They are only two dollars, "the girl answers." And how much is that blue shirt" "It's nine dollars." The boy says, "If I give you twenty dollars, how much will you give back to me?" Nine dollars, and will you buy them now the salesgirl is a little unhappy. "No, it's my maths homework. I can't do it, but now thank you very much, "he says and goes out of the shop.