Passage Three

Each of us carries about half a dozen defective genes. We remain unaware of this fact unless we, or one of our close relatives, are amongst the many millions who suffer from a genetic disease. About one in ten people has, or will develop at some later stage, an inherited genetic disorder, and approximately 2,800 specific conditions are known to be caused by defects in just one of the patient's genes. （第一题答案参考句子）Some single gene disorders are quite common—cystic fibrosis (纤维症) is found in one out of every 2,500 babies born in the Western world—and in total, diseases that can be traced to single gene defects account for about five percent of all admissions to children's hospitals.

  Most of us do not suffer any harmful effects from our defective genes because we carry two copies of nearly all genes, one derived from our mother and the other from our father. The only exceptions to this rule are the genes found on the male sex chromosomes (染色体). Males have one X and one Y chromosome（第二题答案参考句子）, the former from the mother and the latter from the father, so each cell has only one copy of the genes on these chromosomes. In the majority of cases, one normal gene is sufficient to avoid all the symptoms of disease.（第三题答案参考句子） If the potentially harmful gene is recessive (隐性的), then the normal gene will carry out all the tasks assigned to both. Only if we inherit from our parents two copies of the same recessive gene will a disease develop.

  On the other hand, if the gene is dominant, it alone can produce the disease, even if the other one is normal. Clearly only the children of a parent with the disease can be affected, and then on average only half the children will be affected. Huntington's chorea (舞蹈症), a severe disease of the nervous system, which becomes apparent only in adulthood, is an example of a dominant genetic disease.（第五题答案参考句子）

1. What does the author state about the genetic disease?

      A)  Most genetic diseases are developed in childhood.

      B)  The defective genes can cause genetic diseases inevitably.

      C)  Everyone knows clearly that he carries some defective genes which can cause genetic diseases.

      D)  It's very likely that the defects in just one gene can result in as many as 2,800 genetic diseases.√

2. What do you know about the male sex cell?

      A)  Each has only one X chromosome.

      B)  Each has only one Y chromosome.

      C)  Each has either one X chromosome or one Y chromosome.

      D)  Each has both one X chromosome and one Y chromosome.√

3. In most cases, on what occasion can a person avoid suffering from genetic diseases?

      A)  If he has at least one normal gene. √

      B)  When he has two potentially harmful recessive genes.

      C)  Only when he has two normal genes.

      D)  Only if he inherits from his parents two copies of the same recessive gene.

4. Between a couple, if only a mother has a genetic disease, what is very likely to happen to her children?

      A)  All her children will be affected.

      B)  None of her children will be affected.

      C)  They will not get the disease until they grow up.

      D)  Averagely, there is about 50 percent possibility for her children to be affected.√

5. What do you know about Huntington's chorea according to this passage?

      A)  Only adult can be affected by the disease.

      B)  The disease develops because the harmful gene is much powerful than the normal gene.√

      C)  It's a comparatively mild disease.

      D)  It's a disease which can not be cured now.

Passage Four

We are destroying the world's precious ancient forests at an unparalleled rate. In an area of natural forest, the size of a soccer pitch is cut down every two seconds. A quarter of the forest lost in the last 10,000 years has been destroyed in the last 30 years.（第一题答案参考句子） Forest loss has a direct link to loss of biodiversity (生物多样性). The current extinction (灭绝) rate of plant and animal species is around 1,000 times faster than it was in pre-human times—and this will increase to 10,000 times faster by 2050. Scientists predict that the Earth is entering the sixth major extinction event in its history.

  Until now, world maps have not been sufficiently accurate or consistent to reveal which forest areas remain intact, which have been damaged and to what extent.（第二题答案参考句子） This has made it difficult to see which forest areas are most in need of protection. Greenpeace has created a new map of the world's forests, based on the most up-to-date and high-resolution (高分辨率的) satellite imagery and a consistent set of standards.（第三题答案参考句子）

  It shows us the remaining large forest areas and lets us compare them directly and accurately with the extent of Earth's original forest cover for the first time. This groundbreaking research shows that the world's remaining ancient forests are in crisis and that fewer intact forest landscapes than previously thought are left.（第四题答案参考句子） Only intact forest landscapes of several thousands of square kilometers are large enough to sustain healthy population of many larger forest animals like bears, tigers and forest elephants. They are also better able to adapt to the changing global climate.

  To preserve these last intact forests and the biodiversity they support, we must protect large and unbroken areas from further industrial exploitation.（第五题答案参考句子）

  The moment a road is built, the forest and its precious balance of interdependent species begin to be destroyed. These maps are a starting point for monitoring these last large forests landscapes now and in the future and are the baseline for a roadmap to recovery. World governments can use these maps to identify which forest areas are most in need of protection.

1. What do we know about human destruction to the ancient forests nowadays?

      A)  People are destroying them at a higher rate than before. √

      B)  People are destroying them at a lower rate than before.

      C)  The destruction to the ancient forests has nothing to do with the biodiversity.

      D)  It is not likely that the destruction can result in a major extinction.

2. According to the author, how much do we know about the world's forests before the creation of Greenpeace's map?

      A)  We could easily know which forest areas should be protected.

      B)  We didn't know precisely how many forest areas had been destroyed.√

      C)  We knew very clearly the extent to which the forests had been destroyed.

      D)  We had enough evidence to prove how severely the forests had been destroyed.

3. Which of the following does not belong to the characteristics of the new map?

      A)  It has a set of standards of the regular pattern.

      B)  It can provide the latest pictures of the ancient forests.

      C)  It can provide much clearer pictures of the ancient forests.

      D)  It can tell us accurately all the remaining ancient forest areas in the world. √

4. What information can we get from the new map?

      A)  How many forest areas will be destroyed in the near future.

      B)  There are more ancient forests undestroyed than people ever imagined.

      C)  There are fewer ancient forests undestroyed than people ever imagined. √

      D)  How well the biodiversity is protected in the remaining ancient forests.

5. What should we do to protect the last remaining ancient forests according to this passage?

      A)  We should shield them from more damage done by some industrial commercial activities. √

      B)  We should create more maps to know more information about the remaining ancient forests.

      C)  We should call for all the people to fight against the illegal exploitation.

      D)  We must protect every remaining ancient forest area no matter how small it is.