阅读理解。 A "lost tribe" that reached America from Australia may have been the first Native Americans, according to a new theory. If proved by DNA evidence, the theory will break long established beliefs about the southerly migration of people who entered America across the Bering Strait, found it empty and occupied it. On this theory rests the belief of Native Americans to have been the first true Americans. They would be classified to the ranks of escapee, beaten to the New World by Aboriginals (土著人) in boats. To a European, this may seem like an academic argument, but to Americans it is a philosophical question about identity, Silvia Gonzales, of Liverpool University said. Her claims are based on skeletons found in the California Peninsula of Mexico that have skulls quite unlike the broad Mongolian features of Native Americans. These narrow-skulled people have more in common with southern Asians, Aboriginal Australians and peopleof the South Pacific Region. The bones, stored at the National Museum of Anthropology (人类学) in Mexico City, have been carbon-dated and one is 12,700 years old, which places it several thousand years before the arrival of people from the North. "We think there were several migrationwaves into the Americas at different times by different human groups," Dr. Gonzales said."The timing, route and point of origin of the first colonization of the Americas remains a most contentious topic in human evolution." But comparisons based on skull shape are not considered conclusive by anthropologists,so a team of Mexican and British scientists, backed by the Natural Environment Research Council, has also attempted to take out DNA from the bones. Dr. Gonzales declined yesterdayto say exactly what the results were, as they need to be checked, but indicated that they were consistent (一致) with an Australian origin. 1. It is generally considered that the first Native Americans came from ______. [ ] A. North Asia B. Australia C. South Pacific D. South Asia 2. The skeletons found in the California Peninsula of Mexico have ______. [ ] A. the broad skull shape B. the narrow skull shape C. different features of Aboriginal Australians D. the same features of Native Americans 3. The underlined "contentious" is similar in meaning to "______". [ ] A. likely to cause great interest B. difficult to solve C. well-known to all D. likely to cause argument 4. Which of the following statements is true according to the text? [ ] A. Research on skulls can draw an exact conclusion. B. DNA tests have proved the fact that the first Native Americans came from Australian. C. Scientists are still not sure about the origin of the Native Americans.D. People began to enter America across the Bering Strait about 12,700 years ago.