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多黏菌素类抗生素的作用机制是
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已知m、n是方程x2-3x+1=0的两个实根，则2m2+4n2-6n的值为（）。
近代以来，中国社会内忧外患，正是这种严酷现实的强烈刺激，使知识分子的社会责任感变得特别______，而只要有这份责任感在心中______，那先前已经被理智放逐的传统意识，那注重世俗功利和群体价值的精神习惯，就很容易______。依次填入划横线部分最恰当的一项是（）。
After the violent earthquake that shook Los Angeles in 1994, earthquake scientists had good news to report: The damage and death toll could have been much worse.More than 60 people died in this earthquake. (26) comparison, an earthquake of similar intensity that shook America in 1988 (27) 25,000 victims. (28) and deaths were relatively less in Los Angeles because the quake occurred at 4:31 a.m. on a holiday, (29) traffic was light on the city’s highways. In addition, changes made to the construction codes in Los Angeles during the last 20 years have (30) the city’s buildings and highways, making them more (31) to quakes.Despite the good news, civil engineers aren’t (32) on their successes. (33) to their drawing boards are blueprints for improved quake-resistant buildings. The new designs should (34) even greater security to cities where earthquakes often take place.In the past, making structures quake-resistant meant final yet (35) materials, such as steel and wood, which (36) without breaking. Later, people tried to lift a building off its foundation, and (37) rubber and steel between the building and (38) foundation to reduce the (39) of ground vibrations. The most recent designs give buildings (40) as well as concrete and steel supports. Called smart buildings, the structures (41) like living organisms to an earthquake’s vibrations. When the ground shakes and the building (42) forward, the computer would force the building to (43) in the opposite direction.The new smart structures could be very (44) to build. However, they would (45) many lives and would be less likely to be damaged during earthquakes. 32（）
喹诺酮类抗生素的作用机制是
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