It had become an issue since the cloning of Dolly the sheep in Scotland.

自苏格兰的多利羊被克隆后，这已成为一个争议性问题。

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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.

自从1997年多利羊被克隆以来，威斯苏森的电话一直响个不停，人们打电话希望能复制他们的猫、狗、牛和马。

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Dolly the sheep was cloned using a technique called nuclear transfer.

克隆羊“多莉”的问世是应用了一项称为细胞核转移的技术。

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In nineteen ninety-six, a sheep named Dolly became the first animal to be cloned.

VOA: special.2010.03.23

But Ian Wilmut, who created Dolly the sheep, says Advanced Cell's work on cows is encouraging.

FORBES: Dolly The Sheep Dies

Such nuclear transfer produced Dolly the sheep, the world's first cloned mammal, four years ago.

ECONOMIST: Cloning still looks far too dangerous to attempt

An ethical debate on cloning has been brewing ever since Dolly the sheep was produced in 1997.

CNN: Call for ban on human cloning