In July 1989, Dr.Fox and a team of scientists achieved a major scientific breakthrough.Fox discovered the gene (基因) that causes cystic fibrosis (膀胱纤维症) (CF).Many geneticists consider it 's one of the most significantdiscoveries in human genetics.Theresult

In July 1989, Dr.Fox and a team of scientists achieved a major scientific breakthrough.Fox discovered the gene (基因) that causes cystic fibrosis (膀胱纤维症) (CF).Many geneticists consider it 's one of the most significantdiscoveries in human genetics.Theresults of Fox work have helped scientists developtests that identify carriers of the CFgene.They hope his research could cure CF.a testhas been developed to identify peoplerrying the cystic fibrosis gene.The test isbased on knowing where the gene is locatedhe CF gene is a recessive gene.Thismeans a person can carry one copy of the gene andstill not be affected by the disease.However if this person has children with anothererson who carries the Cf genethere is a 25 chance that their children will inherit twoopies of the gene and sufferfrom the disease.The test identifies whether pat for cysticrents carrythe defective CF gene.Researchers are also using Fox discovery to find a curefibrosis.They areworking to produce a drug that will change the activity of the Cf geneId alsoattempting to replace the defective gene with one that functions properly.Itdifficultto produce a drug that changes the Cf gene but does not affect the 100000thergenes of human.But Fox discovery has at least given a chance for the cure othe CF

1.A person with ( ) of a harmful recessive gene will be affected

A.one copy

B two opies

C.no copies

D three copies.

2.We can find answers to the following questions in the passage except ()

A.Do people with CF live longer than they did in the past.

B Describeused to treat CF

C.Evaluate the current methods used to treat CF

D.Describe the drugs used to treat CF

3.The following statements are true except ()

A Only one quarter of people will have chance to have the disease.

B.Fox discovery help scientist develop tests that identify carriers of the CF gene

C.Scientist has already produced a drug to CF

D.To produce a drug is not easy because it should changes the CF gene but notaffectothers

4.The word “recessive” (line 6) probably means ()

A.hidden

B concealing

C.faint

D covered

5.The best title for the passage would be ()

A.Why People Have CF

B.The Drugs Used to Treat CF

C.The Methods of Curing CF

D.TheSignificance of the DiscoveryCystic Fibrosis Gene