下列级数中属于[条件收敛]的是_爱下问搜题

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问题单项选择题

下列级数中属于[条件收敛]的是

答案

参考答案：D

解析：[分析一] (A)，(B)，(C)不是条件收敛．
[*]
其中，[*]发散[*]发散．
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其中，[*]均收敛[*]绝对收敛．
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[*](C)绝对收敛．因此应选(D)．
[分析二] 直接证明(D)条件收敛．
[*]自调下降趋于零(n→+∞)[*]交错级数[*]收敛．又
[*]
而[*]条件收敛．故应选(D)．
[评注] [*]

完形填空

通读下面短文，掌握其大意，然后在各题所给的A，B，C，D四个选项中，选出一个最佳答案。
One Saturday afternoon, a six-year-old girl went for a walk. She crossed a large area of grassland into the woods __36__ she realized that she was lost.
Sitting on a rock and __37__ what to do, she began crying. After a while. she__38__ to walk along a wide path lined with tall trees and thick bushes. __39__ it was getting dark, she saw a small, dark wooden house. She opened the door and __40__ stepped in. Suddenly, she heard a strange noise, and she ran out the door and back to the __41__. Cold and tired, she fell asleep near a __42__.
The girl’s parents were out and her dog, Laddy, was at home. Laddy __43__ that his mistress was in danger. He jumped __44__ a window, breaking the glass. He looked in the fields. But he couldn’t find his mistress anywhere. However, from the ground came a __45__ scent (气味) as he lowered his head. He __46__ the scent and walked across the grassland. Barking __47__ into the air, the dog __48__ through the woods until he found the __49__ . But the girl was not there, so he headed back to the woods. Much to his __50__ , he saw his mistress’ blue shirt in the distance. He __51__ over some bushes and saw the little stream, where the girl was __52__.When she opened her eyes and 53 her dog standing beside her, the girl said, “you 54 me, Laddy,” and she kissed him several times. Seeing their daughter and dog coming back, the parents burst into tears of 55 . That night Laddy had a hero’s supper: a huge meal of steak

C．remembering

D．unwillingly

小题6:A. trees B. woods C grasses. D. bushes

A．satisfaction

B．disappointment

C．embarrassment

单项选择题

狭叶番泻叶主产于（）。

A.红海以东至印度一带

B.尼罗河上游

C.印度尼西亚

D.马来西

E.越南、老挝及柬埔寨