Since sheep and cattle can't survive harsh climates, they needed to be taken south every winter.

由于牛羊不能在恶劣的气候条件下生存，每年冬天都要把它们带到南方去。

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

CNN: Call for ban on human cloning

Jean-Marc has been up on these tilted, boulder-strewn pastures since 5am, milking 250 sheep in the company of a trainee shepherd from Brittany.

BBC: France and Spain��s centuries-old celebration of peace

In the more than three years since scientists in Britain cloned the sheep Dolly, other researchers have successfully cloned sheep, cows, goats, pigs and mice.

CNN: U.S. lawmakers debate limits on human cloning