There is a little boy named Mark. He hopes he could fly like a bird. His parents tell him, “Dear, you can't fly.” “Why can't I? Some birds in the zoo are very big, but they can fly.” The boy can't understand.

    There is another little boy named Barry. He is crippled(跛脚的). He wishes he could walk and run like other children.

    “Why can't I walk or run like other children?” Barry asks his father. His father doesn't know what to say.

    One day, the two boys meet in a park.

    “Do you want to fly like a bird?” Mark asks Barry.

    “No,” Barry says. “ I just wish I could walk and run like you.”

    Mark thinks for a minute, walks to Barry's father and says something into his ear.

    “That's OK,” says the father.

    Mark goes to Barry and says, “Get onto my back. Let's run together.” Then Mark carries Barry and begins to run. He runs faster and faster. He runs across the park with Barry on his back. The crippled boy flaps(拍打) his arms up and down in the wind. He shouts at the top of his voice, “We're flying, Mark! We're flying!”

回答下面5个问题, 每题答案不超过7个词。

下列关于肺泡的表述中，不正确的是（    ）