The impetus()behind the research that led to Dolly was not to find a way to clone humans but rather to develop genetically engineered animals that would serve a variety of purposes.As there are great genetic differences in cattle herds and sheep flocks,breeding copies of selected livestock would increase the efficiency of agricultural productivity and help improve the quality of such commercial products as milk,beef,and wool. As in the management of other breeding schemes,it will be important for scientists to maintain the balance between intense selection of livestock and the maintenance of genetic variability.Preservation of frozen cells from a large number of representatives of different breeds would allow nuclei from those donor cells to be used as required.The ethical issues in animal cloning are perhaps less controversial than with humans;nevertheless,some people worry that producing large numbers of animal clones only increase the likelihood that these animals will be mistreated. Genetic modification of livestock will also provide new opportunities in medicine and research.Today many patients in need of transplants die before organs become available from suitable donors.Cloning pigs has been suggested as a means of rapidly achieving xenotransplantation ()the use of animal organs to replace organs in human patients.Organs transplanted between species are in danger of being destroyed within minutes by the acute immune response of the body receiving the transplant;however, strategies are being developed to modify pigs genetically so that rejection by the immune system may be effectively prevented. 31.According to the passage people object to the use of cloning to produce copies of humans mainly because A.its technique is not good enough B.it is immoral and leads to wrong expectations C.it may lead to parents'unnatural behavior to the copy of them D.it may lead to many people's unemployment 32.Which of the following words can be used to replace the word "well"in Para.1, Line 6? A.easily B.as one would wish C.quite possibly D.skillfully 544The impetus( 推动力) behind the research that led to Dolly was not to find a way to clone humans but rather to develop genetically engineered animals that would serve a variety of purposes. As there are great genetic differences in cattle herds and sheep flocks. breeding copies of selected livestock would increase the efficiency of agricultural productivity and help improve the quality of such commercial products as milk. beef. and wool. As in the management of other breeding schemes. it will be important for scientists to maintain the balance between intense selection of livestock and the maintenance of genetic variability. Preservation of frozen cells from a large number of representatives of different breeds would allow nuclei from those donor cells to be used as required. The ethical issues in animal cloning are perhaps less controversial than with humans; nevertheless. some people worry that producing large numbers of animal clones only increase the likelihood that these animals will be mistreated. Genetic modification of livestock will also provide new opportunities in medicine and research. Today many patients in need of transplants die before organs become available from suitable donors. Cloning pigs has been suggested as a means of rapidly achieving xenotransplantation (异种移植). the use of animal organs to replace organs in human patients. Organs transplanted between species are in danger of being destroyed within minutes by the acute immune response of the body receiving the transplant; however. strategies are being developed to modify pigs genetically so that rejection by the irnrnune system may be effectively prevented. 31. According to the passage people object to the use of cloning to produce copies of humans mainly because 一一一一一· A. its technique is not good enough B. it is immoral and leads to wrong expectations C. it may lead to parents' unnatural behavior to the copy of them D. it may lead to many people' s unemployment 32. Which of the following words can be used to replace the word "well" in Para. 1. Line 6? A. easily B. as one would wish C. quite possibly D. skillfully 544