Cloning is a way of           (make) an exact copy of another animal or plant. Cloning has two           (主要的) uses. Firstly, gardeners use it to produce plants. Secondly, it is           (value) for medical research on animals. Cloning plants is straightforward while cloning animals is very       (复杂的). The procedure is difficult to         (开展). In 1996， scientists succeeded in      (clone) Dolly the sheep. Then came the disturbing news that Dolly was ill.        Dolly lived for six years, Dolly's appearance raised a storm of       (object). Government became nervous and many        (禁止) research into human cloning. Scientists still         whether cloning will help or harm us and where it is leading us.