Thanks to its harsh environment,Antarctica remained largely untouched by humans for many millennia（千年），allowing a thriving ecosystem to evolve.However,since the 1990s,the last true wilderness on the planet is becoming an increasingly popular destination for adventure-seeking tourists.Now,a new study declares that the visitors may be leaving behind harmful bacteria which could devastate all of the area's native bird population.
Humans can infect animals with illnesses such as the flu.Researchers,however,believed that the Antarctic animals were immune to the danger due to the continent's extreme weather.However,microbiologist Marta Cerda-Cuellar was not convinced.She and some colleagues decided to examine waste samples from Antarctic birds for evidence of human bacteria.To ensure the waste was not polluted,the scientists had to collect it from the birds themselves.
The results of their study revealed the presence of several types of human bacteria in the bird waste.This included a common strain（品种）of bacteria that causes food poisoning in humans.The researchers say the bacteria strains were resistant to commonly-used human antibiotics,indicating they were brought in by the visitors,rather than migratory birds.
"These strains,which are a common cause for infections in humans and livestock,do not usually cause death outbreaks in wild animals," says Gonzalez Solis. "However,the emerging of invasive pathogens（病原体）that arrive to highly sensitive populations could have severe consequences and cause the local collapse and extinction of some populations. " The researcher also fears the presence of these bugs could foreshadow（预示）the arrival of other,more deadly,pathogens as the number of tourists people increases.
Experts believe the only way to prevent the mass destruction of the birds is to impose stricter regulations or,at least,put the ones already in place into effect.For example,while the Antarctica Treaty requires visitors to carry their waste back home to safeguard the pristine（原始纯净的）environment,the regulation is rarely enforced.Fortunately,nowadays some officials are taking steps to save the vulnerable birds before it's too late.



What problem is Antarctica facing according to Paragraphs 1&2？ ______

A. The increasing number of birds.
B. The worsening wilderness.
C. The replaced native bird species.
D. The spread of infectious illnesses.

What does the underlined word "devastate" mean？ ______

A. Reject.
B. Protect.
C. Destroy.
D. Benefit.

What do we know about the waste samples from Antarctic birds the scientist collected？ ______

A. There were several types of human bacteria in them.
B. Migratory birds brought these strains of bacteria in.
C. The strains usually cause death outbreaks in wild animals.
D. The invasive pathogens will become more deadly ones soon.

What is the author's attitude towards the future of bird population in Antarctica？ ______

A. Indifferent.
B. Doubtful.
C. Ambiguous.
D. Optimistic.