"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
A. animal cloning is not worth the effort at all
B. animal cloning is absolutely impractical
C. human cloning should be done selectively
D. human cloning is a foolish undertaking
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