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1.设A为m×n阶矩阵，证明：r(ATA)=r(A)；

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皮下的( )。

A. gtt
B. ung
C. qs
D. H
E. Mist

Many years ago there was a huge oil refinery fire. Flames shot hundreds of feet into the air. The sky was thick with black smoke. The heat was so intense that firefighters had to park their trucks a block away and wait for the heat to die down before they could begin to fight the fire. However, it was about to rage out of control. Then, all of a sudden, from several blocks away came a fire truck racing down the street. With its brakes screeching, it hit the curb in front of the fire. The firefighters jumped out and began to battle the blaze. All the firefighters who were parked a block away saw this, and they jumped into their trucks, drove down the block and began to fight the fire, too. As a result of that cooperative effort, they were just barely able to bring the fire under control. The people who saw this teamwork thought: "My goodness, the man who drove that lead fire truck—what an act of bravery!" They decided to give him a special award to recognize him for his bravery in leading the charge. At the ceremony the mayor said, " Captain, we want to honour you for a fantastic act of bravery. You prevented the loss of property, perhaps even the loss of life. If there is one special thing you could have — what would it be" Without hesitation, the captain replied, "Your Honour, a new set of brakes would be nice!\ Which of the following statements is NOT mentioned in the passage

A. The fire was so strong that it could be hardly under control in the beginning.
B. The captain was awarded by the mayor for his bravery.
C. People were astonished by what the driver of the lead fire truck did.
D. People who were saved wrote to the firefighters to express their thanks.

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问题一：结合“给定资料”，简要介绍西方发达国家公路管理的相关措施。 [要求] 语言简练、准确全面，不超过200字。

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主要降总胆固醇兼降甘油三酯的是( )。

A. 扎贝特
B. 洛伐他汀
C. 海鱼油
D. 硝苯地平
E. 普罗布考

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