完形填空。 What is a clone? A clone is a copy-a genetic (基因的) copy. Genes (基因) are the in-structions for life. They 1 a cell what to do and how to do it. Genes make 2 plant or animal different and unique. A clone has the same genes 3 the original organism (生物体). Cloning is not new. 4 have been cloned for centuries. Many new plants are grown from cuttings (插枝) from the original plants. One benefit of cloning is that we can make many copies of the best and healthiest plants. It's 5 more difficult to clone animals than plants. In 1997 scientists succeeded in 6 a sheep. The creation of Dolly, the Cloned sheep, caused great attention around the world in no time. Scientists had tried to clone other animals like frogs before that, but they failed Frogs died as tadpoles (蝌蚪), never living 7 to become adult frogs. It may soon be 8 to clone many types of animals. Will we also 9 clone human organs (器官), or even a whole human being? Maybe now the question is not whether we can clone humans, but 10 should we clone humans? (     )1．A．keep (     )2．A．each (     )3．A．for (     )4．A．Plants (     )5．A．many (     )6．A．clones (     )7．A．long enough (     )8．A．helpful (     )9．A．must (     )10．A．except B．make B．neither B．from B．Animals B．much B．cloning B．short enough B．difficult B．should B．except for C．tell C．both C．with C．Life C．few C．cloned C．enough long C．possible C．can C．instead D．let D．none D．as D．Humans D．little D．to clone D．enough short D．new D．be able to D．instead of