Who would be pardoned according to the news
A. Those having no connection with recent bombings.
B. Those who give up their weapons voluntarily.
C. Those who cooperate with the government.
D. Those who killed the American hostage.
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u=f（x，y），x=rcosθ，y=sinθ，f具有一阶、二阶连续的偏导数，则urθ（）。
A. -fx·sinθ+fy·cosθ
B. rsinθcosθ(fyy-fxx)-fx·sinθ+fy·cosθ
C. rcos2θ·fxy-fx·sinθ+fy·cosθ
D. rsinθcosθ(fyy-fxx)+rcos2θ·fxy-fx·sinθ+fy·cosθ
What did the protestors demand
A. Resignation of the president.
B. Improvement in economy.
Changes in banking rules.
D. Increase in employment.
"Let's go to the museum this afternoon. There's a wonderful exhibition." "OK.___________ we meet at the bus stop"
A. Will
B. Shall
Can
D. Should
白色平行光垂直入射到间距d=0.25mm的双缝上，距缝500mm处放置屏幕，则第二级明纹彩色带的宽度（设白色光的波长范围为400～760nm）为（）。
A. 0.74mm
B. 1.44mm
C. 2.16mm
D. 2.88mm
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