A、Whit a knife. B、On the edge of some metal. C、On some glass. D、On a piece of paper. D这是一道细节题。在对话一开始时，W问M是不是把自己割伤了，M回答说是的，被这张纸的

M: Ow ! That hurts !
W: What happened? Did you cut yourself?
M: Yes—on the edge of this paper. How can such a little cut hurt so much? I’m not even bleeding, but my finger really hurts.
W: You know, I read something about that. It turns out that a little cut on a finger can hurt a lot more than a big cut somewhere else.
M: Why? That doesn’t make any sense.
W: Actually, it does. There are more nerve endings in your hands than almost anywhere else in the body, and it’s the nerve endings that allow you to feel pain.
M: I guess that’s true.
W: Also, a little cut like yours won’t damage the nerve endings, just irritate them. If they were dam aged. you’d feel less pain, but the wound could be more serious.
M: So I suppose I should be happy my finger hurts so much?
W: Right. Now go get yourself a bandage.
M: Why? You just told me it’s not serious.
W: It’s not, but it does seem to be bothering you. Putting a bandage over the cut will keep the skin from drying and will help the skin stay together. If the skin stays together, the nerve endings won’t be exposed, and the cut will hurt less.