D．some extinct species may be cloned, but not survive

　　解析　由even if extinct animals were brought back, they could not survive in today's world.(即使灭绝的动物能够被克隆回来，他们也无法在现今的世界中存活)可知。

　　答案　D

　　D

　　The United States government wants to know what the public thinks about its findings on the safety of cloned animals.

　　The Food and Drug Administration says meat and milk from clones of adult cattle, pigs and goats are safe to eat. An F．D.A.official called them “as safe to eat as the food we eat every day.” And when those clones reproduce sexually(有性繁殖), the agency says, their offspring(后代) are safe to eat as well. But research on cloned sheep is limited. So the F．D.A.proposes that sheep clones not be used for human food.

　　The United States this year could become the first country to approve the sale of foods from cloned animals. First, however, the public will have ninety days to comment on three proposed documents. On December 28th the F．D.A.released a long report, called a draft risk assessment, along with two policy documents.

　　The agency says it must receive comments by April second. The F．D.A.seemed ready to act several years ago, but an advisory committee called for more research.

　　For now, the government will continue to ask producers to honor a request that they not sell foods from cloned animals.

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