皮样囊肿起源于（） A.皮脂腺 B.胚胎发育残留的上皮 C.舌盲孔导管上皮 D.鳃裂

连一连。

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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 people of 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 migration waves 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 yesterday to say exactly what the results were, as they need to be checked, but indicated that they were consistent(一致) with an Australian origin.

小题1:It is generally considered that the first Native Americans came from ________.

A．North Asia

B．Australia

C．South Pacific

D．South Asia小题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小题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小题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.

预防医学是研究（）

A.对已发生疾病的治疗和控制的科学

B.疾病在人群的流行和采取有效措施

C.疾病发生、发展、转归过程和专门规律的科学

D.预防疾病性质、任务、方法和规律的专门科学

E.疾病发生和消除疾病直接或间接因素

某村村民甲某与乙某于2000年结伴到深圳打工，并于同年参加了城镇职工基本养老保险，2010年末二人一同辞去工作返乡。

乙某决定不再外出务工，而是留在家乡务农，则以下说法正确的是（）。

A.乙某的城镇职工基本养老保险统筹账户缴费记录失效

B.乙某的个人账户失效

C.乙某可自由选择按城镇职工基本养老保险制度享受待遇，或转入新型农村社会养老保险

D.乙某应退出城镇职工基本养老保险

下列说法错误的是（ ）。

A． Caption为只读属性，运行时对象的名称不能改变

B． 设置Height或Width的数值单位为twip，是1点的1/20

C． Icon属性用来设置窗体最小化时的图标

D． 用来激活属性窗口的快捷键是F4键