制物种的多样性。

　　克隆对人类有益还是有害还不清楚。为了避免失去控制，强制性的政府法规将不得不控制克隆。

　　【参考范文】

　　Frankenstein, a scientist created a creature identical to a human being using the technique-cloning.His black hair and white teeth contrast horribly with his wrinkled yellow skin and black lips.It terrifies everyone seeing him.

　　Now some scientists are trying to clone humans, which is controversial.The contradictory opinions are as follows.Those for the idea think we can rely on the clone to resist or cure some diseases.While those against it think cloning will restrict the biodiversity of the breed.

　　Whether cloning will be beneficial or harmful to human beings is unknown.To avoid getting out of control，compulsory government regulations will have to control cloning.