Thanks to its harsh environment，Antarctica remained largely untouched by humans for many millennia，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 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（品種）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（候鳥）.
   "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 or invasive pathogens（病原體）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 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 environment，the regulation is rarely enforced.Nowadays，some officials are taking steps to save the vulnerable birds before it's too late.

（1）What problem is Antarctica facing according to Paragraph 1&2？

D

D

A．The increasing number of tourists.
B．The worsening wilderness.
C．The replaced native bird population.
D．The spread of infectious illnesses.
（2）What does the underlined word "devastate" mean？

A

A

A．Destroy.
B．Increase.
C．Protect.
D．Benefit.
（3）Why did the scientists need to catch some Antarctic animals？

B

B

A．To treat their illness.
B．To get their waste.
C．To raise them as pets.
D．To study their lifestyles.
（4）What did the scientists prove in their study？

C

C

A．Bacteria can be killed by human antibiotics.
B．Extreme weather keeps Antarctic animals healthy.
C．Humans bring bacteria to Antarctica.
D．Antarctic animals are immune to human bacteria.