把一个长方体的长削去 13 ，宽、高各削去 14 后，体积比原来少_刷题宝

题干

把一个长方体的长削去

1

3

，宽、高各削去

1

4

后，体积比原来少（）

A： $\frac{2}{5}$

B： $\frac{1}{2}$

C： $\frac{5}{8}$

上一题下一题 0.0难度选择题更新时间:2016-07-27 03:50:12

答案(点此获取答案解析）

C

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____ Mrs. Li wants to send her daughter to take some piano lessons during the coming summer holiday.
____ Betty and her boyfriend want to spend the weekend to watch something new. They both like dancing.
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A. Watch Your Neck: This modern ballet is telling the story of “Dracula” which is the classic novel by Irish playwright Bram Stoker. Time: 8:30 pm, February 2-9 Tel:98558588
B. Children's Activity Center
Tel: 66589982
Add: No. 2 Zhongshan Road (Singing lessons, piano lessons and dancing lessons.)
C. Art Show: A total of 10 artists living close to each other are jointly giving an art exhibition.
D. Peking Opera: Mei Lanfang’s brave fighting against the Japanese during the war of Resistance against Japanese will open your mind.
E. Foreign Book Center: More and more increasing learning English books and newspapers, CDs. ect.
F. The Changcheng hotel: Five star hotel. Looking for much experienced receptionists. Tel: (010)55883326
G. Car-Hire Service: 12 seat Forit transit van for hire in Zhujing Business and Private Hire. We have English-speaking drivers.

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________ Teacher’s Day is just around the corner．I’ll give my teacher a gift, _____ one that is special and unforgettable．

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亚洲西南与非洲相连,二者之间的分界线是 ( )

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— What do you suppose ______ her look so upset?
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同类题5

某科学兴趣小组学习二氧化锰（MnO₂）催化分解过氧化氢的实验后，进行如下实验：

a．选择装置并检查气密性．

b．称取0.1克的二氧化锰（MnO₂）粉末加入容器中．

c．量取50毫升溶质质量分数约5%的过氧化氢溶液加入容器中，记录一定时间内收集到的气体体积．改变二氧化锰的质量，重复上述实验，记录数据如表．（溶解到水中的氧气忽略不计）

时间/秒	生成氧气的体积/毫升
时间/秒	0.1克MnO₂	0.2克MnO₂	0.3克MnO₂	0.4克MnO₂
40	49	61	75	86
80	77	87	90	92
120	89	92	92	92
160	92	92	92	92

①写出过氧化氢溶液与二氧化锰混合物制取氧气反应的文字或符号表达式____．

②该学习小组利用上述发生装置中的____（填“A”或“B”）与如图装置中的____（填编号）连接测量O₂的体积．

③实验结论：在相同条件下，____，双氧水分解得越快．

④实验反思：由上述实验测得的氧气体积总是偏大的可能原因是____．

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