Jack is very fat. He is worried about his health, so he goes to see his {#blank#}1{#/blank#}.

    "You are 100 kilograms. It's very {#blank#}2{#/blank#}. You must lose about 20 kilograms." The doctor told him.

    "Oh, what should I do, Doctor?"

    "You should {#blank#}3{#/blank#}5 kilometers a day for a month."

    Jack goes home and does these things.{#blank#}4{#/blank#}days later, he calls the doctor.

    "Doctor," he says, "I'm calling to tell you about my weight(重量). I'm 80 kilograms now. But I'm 150 kilometers away from {#blank#}5{#/blank#}. I don't know how to get back!