A.studies produce useful results
B.adults need to be taught like children
C.1anguage learning takes place effectively
D.immigrants want to learn another language
36、
根据下列材料,回答36-50题
DNA Fingerprinting
DNA is the genetic material found within the cell nucleus of all living things.In mammals the strands of DNA are grouped into structures called chromosomes.With the exception of identical siblings(as in identical twins),the complete DNA of each individual is unique.
DNA fingerprinting is sometimes called DNA typing.It is a method of identification that compares bits of DNA.A DAN fingerprint is constructed by first drawing out a DNA sample from body tissue or fluid such as hair,blood,or saliva.The sample is then segmented using enzymes,and the segments are arranged by size.The segments are marked with probes and exposed on Xray film,where they form a pattern of black barsthe DNA fingerprint.If the DNA fingerprints produced from two different samples match,the two samples probably came from the same person.
DNA fingerprinting was first developed as all identification technique in 1985.Originally used to detect the presence of genetic diseases,it soon came to be used in criminal investigations and legal affairs.The first criminal conviction based on DNA evidence in the United States occurred in l988.In criminal investigations,DNA fingerprints derived from evidence collected at the crime scene are compared to the DNA fingerprints of suspects.Generally,coups have accepted the reliability of DNA testing and admitted DNA test results into evidence.However,DNA fingerprinting is controversial in a number of areas:the accuracy of the results,the cost oftestin9,and the possible misuse of the technique.
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