第十七篇：（Unit 5,Passage 1）

A controversy erupted in the scientific community in early 1998 over the use of DNA (deoxyribonucleic acid ) fingerprinting in criminal investigations. DNA fingerprinting was introduced in 1987 as a method to identify individuals based on a pattern seen in their DNA, the molecule of which genes are made. DNA is present in every cell of the body except red blood cells. DNA fingerprinting has been used successfully in various ways, such as to determine paternity where it is not clear who the father of a particular child is. However, it is in the area of criminal investigations that DNA fingerprinting has potentially powerful and controversial uses.

DNA fingerprinting and other DNA analysis techniques have revolutionized criminal investigations by giving investigators powerful new tools in the attempt to trove guilt, not just establish innocence. When used in criminal investigations, a DNA fingerprint pattern from a suspect is compared with a DNA fingerprint pattern obtained from such material as hairs or blood found at the scene of a crime. A match between the two DNA samples can be used as evidence to convict a suspect.

The controversy  in 1998 stemmed form a report published in December 1991 by population geneticists Richard C. Lewontin of Harvard University in Cambridge, Mass., and Daniel L. Hartl called into question the methods to calculate how likely it is that a match between two DNA fingerprints might occur by chance alone. In particular, they argued that the current method cannot properly determine the likelihood that two DNA samples will match because they came from the same individual rather than simply from two different individuals who are members of the same ethnic group. Lewontin and Hartl called for better surveys of DNA patterns methods are adequate.

In response to their criticisms, population geneticists Ranajit Chakraborty of the University of Texas in Dallas and Kenneth K.Kidd of Yale University in New Haven, Conn., argued that enough data are already available to show that the methods currently being used are adequate. In January 1998, however, the federal Bureau of Investigation and laboratories that conduct DNA tests announced that they would collect additional DNA samples form various ethnic groups in an attempt to resolve some of these questions. And, in April, a National Academy of Sciences called for strict standards and system of accreditation for DNA testing laboratories.

1.Before DNA fingerprinting is used, suspects____.
A.would have to leave their fingerprints for further investigations
B.would have to submit evidence for their innocence
C.could easily escape conviction of guilt
D.cold be convicted of guilt as well

2.DNA fingerprinting can be unreliable when ____.
A.the methods used for blood- cell calculation are not accurate
B.two different individuals of the same ethnic group may have the same DNA fingerprinting pattern
C.a match is by chance left with fingerprints that happen to belong to two different individuals
D.two different individuals leave two DNA samples.

3.To geneticists like  Lewontin and Hartl, the current method ____.
A.is not so convincing as to exclude the likelihood that two DNA samples can never come from two individuals
B.is arguable because two individuals of the same ethnic group are likely to have the same DNA pattern.
C.Is not based on adequate scientific theory of genetics
D.Is theoretically contradictory to what they have been studying

4.The attitude of the Federal Bereau of Investigation shows that ____.
A.enough data are yet to be collected form various ethnic groups to confirm the unlikelihood of two DNA samples coming from two individual members
B.enough data of DNA samples should be collected to confirm that only DNA samples form the same person can match
C.enough data are yet to be collected from various ethnic groups to determine the likelihood of two different DNA samples coming form the same person
D.additional samples from various ethnic groups should be collected to determine that two DNA samples are unlikely to come from the same person

5.National Academy of Sciences holds the stance that ____.
A.DNA testing should be systematized
B.Only authorized laboratories can conduct DNA testing
C.The academy only is authorized to work out standards for testing
D.The academy has the right to accredit laboratories for DNA testing

第十七篇答案：CBABB


第十八篇：（Unit 5,Passage 2）

Racket, din clamor, noise, whatever you want to call it, unwanted sound is America’s most widespread nuisance. But noise is more than just a nuisance. It constitutes a real and present danger to people’s health. Day and night, at home, at work, and at play, noise can produce serious physical and psychological stress. No one is immune to this stress. Though we seem to adjust to noise by ignoring it, the ear, in fact, never closes and the body still responds—sometimes with extreme tension, as to a strange sound in the night.

The annoyance we feel when faced with noise is the most common outward symptom of the stress building up inside us. Indeed, because irritability is so apparent, legislators have made public annoyance the basis of many noise abatement programs. The more subtle and more serious health hazards associated with stress caused by noise traditionally have been given much less attention. Nevertheless, when we are annoyed or made irritable by noise, we should consider these symptoms fair warning that other thing may be happening to us, some of which may be damaging to our health.

Of many health hazards to noise, hearing loss is the most clearly observable and measurable by health professionals. The other hazards are harder to pin down. For many of us, there may be a risk that exposure to the stress of noise increases susceptibility to disease and infection. The more susceptible among us may experience noise as a complicating factor in heart problems and other diseases. Noise that causes annoyance and irritability in health persons may have serious consequences for these already ill in mind or body.

Noise affects us throughout our lives. For example, there are indications of effects on the unborn child when mothers are exposed to industrial and environmental noise. During infancy and childhood, youngsters exposed to high noise levels may have trouble falling asleep and obtaining necessary amounts of rest.

Why, then, is there not greater alarm about these dangers? Perhaps it is because the link between noise and many disabilities or diseases has not yet been conclusively demonstrated. Perhaps it is because we tend to dismiss annoyance as a price to pay for living in the modern world. It may also be because we still think of hearing loss as only an occupational hazard.

1.In Paragraph 1, the phrase “immune to” are used to mean ___.
A.unaffected by
B.hurt by
C.unlikely to be seen by
D.unknown by

2.The author’s attitude toward noise would best be described as ___.
A.unrealistic
B.traditional
C.concerned
D.hysterical

3.Which of the following best states the main idea of the passage?
A.Noise is a major problem; most people recognize its importance.
B.Although noise can be annoying, it is not a major problem.
C.Noise is a major problem and has not yet been recognized as such.
D.Noise is a major problem about which nothing can be done.

4.The author condemns noise essentially because it ___.
A.is against the law
B.can make some people irritable
C.is a nuisance
D.in a ganger to people’s health

5.The author would probably consider research about the effects noise has on people to be ___.
A.unimportant
B.impossible.
C.a waste of money
D.essential

第十八篇答案：ACCDD

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