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用于确证哺乳动物致癌物的试验是
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A．脂水分配系数与毒效应B．分离度与毒效应C．挥发度和蒸气压与毒效应D．分散度与毒效应E．纯度与毒效应 As2O3细粉状的比粗粉状的毒性大（）
The teacher got so much（）(satisfy) with what he did. He was too careless to do anything well.
On July 12, 1993, a young professor of American history named Frederick Jackson Turner stood up to speak. The scene was the American History Congress at the Chicago World’s Fair. (62) His paper was titled "The significance of the Frontier in American History." Turner had a new idea. (63) And many historians who heard him recognized that he had come upon a simple theory that seemed right.To Turner, the frontier was one of the most powerful forces shaping the American character. He pointed out that the frontier was a place for new beginnings, a place where men and women could build new lives. Thus, the frontier represented hope and opportunity to Americans. Turner also pointed out that these new lives on the frontier were shaped by tile hardships of surviving in the wilderness. Thus, life on the frontier produced determination in Americans and made them believe in the value of work. (64)According to Turner’s theory, the frontier was a place where everyone had to struggle equally hard. (65) Thus, frontier life helped shape the American ideal of equality, independence, and democracy. His paper was titled "The significance of the Frontier in American History."
[听力原文]M: Did I hear that this is your last lecture hereW: Yes. I’ve accepted a better teaching position elsewhere. What will the woman do（）
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