2009年12月英語(yǔ)六級(jí)閱讀理解全真模擬題(六)

　　Passage Four

　　Questions 36 to 40 are based on the following passage.

　　“I’ve never met a human worth cloning,” says cloning expert Mark Westhusin from his lab at Texas A&M University. “It’s a stupid endeavor.” That’s an interesting choice of adjective, coming from a man who has spent millions of dollars trying to clone a 13-year-old dog named Missy. So far, he and his team have not succeeded, though they have cloned two cows and expect to clone a cat soon. They just might succeed in cloning Missy this spring—or perhaps not for another 5 years. It seems the reproductive system of man’s best friend is one of the mysteries of modern science.

　　Westhusin’s experience with cloning animals leaves him upset by all this talk of human cloning. In three years of work on the Missy project, using hundreds upon hundreds of dog’s eggs, the A&M team has produced only a dozen or so embryos (胚胎) carrying Missy’s DNA. None have survived the transfer to a surrogate (代孕的) mother. The wastage of eggs and the many spontaneously aborted fetuses (胎) may be acceptable when you’re dealing with cats or bulls, he argues, but not with humans. “Cloning is incredibly inefficient, and also dangerous,” he says.

　　Even so, dog cloning is a commercial opportunity, with a nice research payoff. Ever since Dolly the sheep was cloned in 1997, Westhusin’s phone has been ringing with people calling in hopes of duplicating their cats and dogs, cattle and horses. “A lot of people want to clone pets, especially if the price is right,” says Westhusin. Cost is no obstacle for Missy’s mysterious billionaire owner; he’s put up $3.7 million so far to fund A&M’s research.

　　Contrary to some media reports, Missy is not dead. The owner wants a twin to carry on Missy’s fine qualities after she does die. The prototype is, by all accounts, athletic, good-natured and supersmart. Missy’s master does not expect an exact copy of her. He knows her clone may not have her temperament. In a statement of purpose, Missy’s owner and the A&M team say they are “both looking forward to studying the ways that her clones differ from Missy.”

　　Besides cloning a great dog, the project may contribute insight into the old question of nature vs, nurture. It could also lead to the cloning of special rescue dogs and many endangered animals.

　　However, Westhusin is cautious about his work. He knows that even if he gets a dog pregnant, the offspring, should they survive, will face the problems shown at birth by other cloned animals: abnormalities like immature lungs and heart and weight problems~ “Why would you ever want to clone humans,Westhusin asks, “when we’re not even close to getting it worked out in animals yet?”