外研版选修三册第五单元听力练习

Unit 5 Learning from nature

Rose: I just read this interesting story about a new medical breakthrough.

Dave: Really, what was the story about?

Rose: Scientists have learnt how to grow bone by using coral.

Dave: Really? How does that help anyone?

Rose: Well, it helps people who are injured or who have gotten cancer and have lost some bone tissue. Previously, doctors would take some bone from somewhere else and join it to the bone they already have.

Dave: But where would they get that bone from?

Rose: They could get the bone from the patient's own body. However, this is only good for a small amount of bone, as most people already need almost all their bone tissue. They can also get bone from dead bodies, but this still presents problems.

Dave: Which is what?

Rose: Usually, this is most successful if only a small amount of bone needs to be replaced. But what about if you need a lot of bone? When they try to replace a lot of bone, the failure rate is quite high, and there can be problems. To solve this issue, scientists looked at how coral grows. You see, when coral grows, it first builds a frame of hard tissue. Then coral grows into that frame. Scientists thought, why not do the same thing with bone?

Dave: That's very impressive. How did it work?

Rose: Well, scientists first harvested some coral, and then theated it so that only the hard-tissue frame remains. They then covered it with growth chemicals, and put it in the place where they wanted the bone to grow.

Dave: How long did it take for the bone to grow back?

Rose: About six months or so. During that time, the patient should avoid running and jumping.

Dave: That's very interesting!