根据短文，选择正确选项。
One day, the teacher asks the boys and girls a question. “Swallows（燕子） fly to the south before winter1,”he says. “But why don't cats and dogs do2?” Fox lifts （举） his3as usual. “Yes, Fox?” says the teacher4. Fox stands （站） up and says, “5they have no wings （翅膀）.”
