请教几道800SCORE的逻辑题

The body of anyone infected by virus X will, after a week, produce antibodies to fight the virus; the antibodies will increase in number for the next year or so There is now a test that reliably indicates how many antibodies are present in a person's body. If positive, this test can be used during the first year of infection to estimate to within a month how long that person has had the virus. Which one of the following conclusions is best supported by the statements above?

A) Antibodies increase in number only until they have defeated the virus.

B) Without the test for antibodies, there is no way of establishing whether a person has virus X.

C) Antibodies are produced only for viral infections that cannot be fought by any other body defenses.

D)  If a person remains infected by virus X indefinitely, there is no limit to the number of antibodies that can be present in the person's body.

E)        Anyone infected by virus X will for a time fail to exhibit infection if tested by the antibody test.

In a monogamous culture, 90% of the adults are married. The average number of children per family is five and over-population is a threat. Programs to encourage birth-control have been ineffective. It has been suggested that this failure is due to these programs ignoring a tradition that values male children very highly, so that every parent wants to have at least one son. It is proposed that couples be encouraged to use birth-control measures after the birth of their first son. If this proposal is widely accepted in the culture, we may expect that:

A) the rate of population increase will be slowed, and future generations will contain a disproportionately high number of females.

B) the rate of population increase will be slowed, and the gender balance in future generations will remain as it is at present.

C) the rate of population growth will remain the same, and future generations will contain a disproportionately high number of females.

D) there will be no significant effect either on population growth or on gender balance.

E) the population will decline precipitously, because approximately half of all families will have only a single child.

The report released by the interior ministry states that within the past 5 years the national land-reclamation program has created a 19 percent increase in arable land within the country. If these figures are accurate, the program has been a huge success. Senator Cox, a distinguished mathematician and a woman of brilliance, maintains, however, that the reclamation program could not possibly have been successful. Clearly, therefore, the figures cited in the report cannot be accurate. The argument above exhibits an erroneous pattern of reasoning most similar to that exhibited by which one of the following?

A) Albert's father claims that Albert does not know where the spare car keys are hidden. Yesterday however, Albert reported that he had discovered the spare car keys in the garage toolbox, so his father's claim cannot be true.

B) Gloria's drama teacher claims that her policy is to give each student the opportunity to act in at least one play during the year but, since Gloria, who attended every class, reports that she was not given such an opportunity the teacher's claim cannot be true.

C) Amos claims that he can hold his breath under water for a full hour. Dr. Treviso, a cardiopulmonary specialist, has stated that humans are physiologically incapable of holding their breath for even half that long; so Amos' claim cannot be true.

D) Evelyn reports that she got home before midnight. Robert, who always knows the time, insists that she did not. If Robert is right, Evelyn could not possibly have listened to the late news; since she admits not having listened to the late news, her report cannot be true.

E) Moira, after observing the finish of the 60-kilometer bicycle race, reports that Lee won with Adams a distant third. Lomas, a bicycle engineering expert, insists, however, that Lee could not have won a race in which Adams competed; so Moira's report cannot be true.

这几道题怎么也想不明白，考的是什么能力，如何解题？