皮皮学，免费搜题
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【单选题】
函数 在区间 内函数的导数为正，且 ≤0，则函数 在 内有A.
<0< /div>
B.
>0
C.
= 0
D.
无法确定
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知识点：
皮皮学刷刷变学霸
举一反三
【单选题】设函数y=f(-x 2 )，则dy等于( )
A.
xf'(-x 2 )dx
B.
-2xf'(-x 2 )dx
C.
2f(-x 2 )dx
D.
2xf'(-x 2 )dx
【简答题】求势函数u(x，y)，使得 (1)du=(3x 2 -3y 2 +4)dx-6xydy (2)du=(e x siny+2xy 2 )dx+(e x cosy+2x 2 y)dy.
【简答题】Passage One Questions 56 to 60 are based on the following passage. Last week I visited one of my old neighborhoods in Washington D.C. I had not been there for twenty years and as I walked along the st...
【简答题】Professor Martin’s report says that children who attend a number of different schools, because their parents have to move around the country, probably make slow progress in their studies. There are al...
【简答题】Passage Two Questions 1 to 5 are based on the following passage. Forgiving is easy. Forgetting the experience that comes before the forgiveness, however, always remains with us. Choosing to forgive me...
【单选题】关于藻类、苔藓、蕨类植物的叙述，错误的是（ ）
A.
藻类植物没有根、茎、叶的分化
B.
苔藓、蕨类植物的生活环境离不开水
C.
苔藓靠孢子繁殖后代，蕨类植物靠种子繁殖后代
D.
苔藓对二氧化硫等有毒气体敏感，常作为空气污染程度的指示植物
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