The United States this year could become the first country to agree to the sale of foods from cloned animals. First, however, the public will have ninety days to comment on three suggested documents. On December 28th the FDA 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 FDA seemed ready to act several years ago, but a 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.

　　Clones are still rare. They cost a lot and are difficult to produce.

　　The FDA says most food from cloning is expected to come not from clones themselves, but from their sexually reproduced offspring. It says clones are expected to be used mostly as breeding animals to spread good qualities.

　　Public opinion studies show most Americans do not like the idea of food from cloned animals. But this research also shows the public knows little about cloning.

　　Cloning differs from genetic engineering. A cell taken from a so-called donor animal is grown into an embryo (胚胎) in the laboratory. Next, the embryo is placed into the uterus (子宫) of a female animal. If the process is successful, the pregnancy reaches full term and a genetic copy of the donor animal is born.

　　41. What’s the main purpose of the passage?

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