听力原文：M: We continue with the World of Investigation. Laura, an identical twin, has agreed to contribute to our investigations. I must apologize for the fact that Laura's twin cannot be here tonight. And I'd like to tell you, Laura, how sorry we are. You and your sister are very close, aren't you? W: Of course we are. M: Interesting! You said 'of course' Don't you think there are quite a few sisters who aren't close? W: Sarah and I aren't just sisters. We're identical twins. M: I take your point. How identical are you, in fact? W: Both blonde, with brown eyes. Same height, same weight, same size. Even shoes. M: As you're the same size, have you always dressed alike? W: Oh yes. I'm told it started when we were babies. Mum made a feature of her twins. And then we got into the habit of buying two of everything. M: And you've never minded having a double identity? I mean ... another person exactly like you? W: Sarah isn't exactly like me. We may look identical, but I remember our boyfriends couldn't tell us apart. M: Didn't that cause problems? W: For them, perhaps. Not for us. We couldn't stop laughing. M: I think you said you and Sarah weren't exactly alike? Just what did you mean by that? W: Sarah has a well -fed happy husband and four healthy children. When she was washing up, I was learning to type. When she was knitting, I was writing articles lot the school newspaper. When she was having her second child, I was in Panama, doing my first job for United Information Services. See what I mean? M: And haven't you got a healthy husband and happy children? W: You must be joking. There's never been the time ... or the inclination. M: Laura, you've made some-very interesting points. I gather that you don't feel that behaviour is purely genetic ... that there might be some element of environment or choice or even perhaps... W: Shall I conclude? Sarah and I are identical twins ... in appearance, that is ... but it's a fact that life has presented us with different opportunities, so we've led very different lives. (23)