D．The Debate about Cloning human embryos

答案　D　[主旨大意题。本文主要介绍了克隆技术。A、B和C项答案均比较片面，D项比较合适。]

My wife and I，recently driving through Arizona，stopped at a "collector's shop"in Tucson，where many kinds of stones and minerals were on display. During the visit，we were taken into a small room where ordinary­looking rocks were laid out on shelves. Had I seen them on some hillside，I would not have given them a second thought. Then the man closed the door so that the room was in total darkness and turned on an ultraviolet(紫外线的)lamp. Instantly，the rocks leaped into a kind of glories. Brilliant colors of an indescribable beauty were there before our eyes: a certain power had been switched on，and a hidden world leaped into life.

As I look at my universe and walk among my fellow humans，I have the deep belief that hidden realities are all around us: there in the physical world，and there also in the human world.

I believe，then，that my chief job in life is to switch on an extra power so that I can see what my naked eyes，or my naked mind，cannot see now. I believe that I have to do this particularly with my human fellows. My ordinary eyes tend to stop short at those envelopes we call human bodies. But we have learned that by turning on a certain power we can see through to the inside of these envelopes.

We call this extra power "imagination"．At its highest，we call it"empathy"，the power to see through and to feel through to the inner life of other human beings. When we turn on this lamp of imaginative sensitivity，we make the ordinary human beings around us come excitingly alive.

When we are aware that there are glories of life still hidden from us，we walk humbly (谦逊地)before the Great Unknown. But we do more than this: we try to increase our powers of seeing and feeling so that we can turn what is still unknown into what is warmly and understandingly known. This，I believe，is our great human adventure.

5．Why does the writer mention their visit to the collector's shop?

A．To introduce the topic.