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食品防腐方法的研究 夏天，煮沸的肉汤很快就会腐败变质。科学家推测，变质的肉汤里面可能生出了无数的细菌。那么，这些细菌是从哪里来的呢？对此，法国生物学家巴斯德（1822年－1895年）进行了认真的研究。他把新鲜、清澈的肉汤装入一个玻璃瓶里，然后把瓶颈烧软并拉成的形状。随后，他再次煮沸瓶里的肉汤。这样，尽管肉汤通过弯曲的瓶颈与外界相通，但是4年过去了，静置的肉汤仍然新鲜如初。怎样解释这一切呢？巴斯德认为，纯净的肉汤是永远不会生出细菌的。问题是出在空气上，空气中飘浮着细菌和芽孢，它们飘落到肉汤里，才使肉汤腐败变质了。 瓶里的肉汤之所以长久不腐败，就是因为空气中的细菌和芽孢不能进入肉汤的缘故。为了证实自己的看法，巴斯德轻轻地摇动静置了4年的瓶。不久，瓶内的肉汤果然腐败了。人们还根据巴斯德的实验结果，研究出了食品长期防腐的办法，这就是现在普遍生产的各种罐头食品。 根据以上材料，分析回答： (1)食物腐败变质的原因是_________。 (2)食品要长期防腐必须防止食品被_________感染。 (3)科学研究的基本方法包括：_________、_________和_________、_________、_________等，上述材料中巴斯德的研究工作主要是：_________法。 (4)分析材料可以看出，实验法应当有5个步骤：①．_________②．_________③．_________④．_________⑤．_________
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【多选题】About the development of cardiovascular system, which ones are right( )
A.
derive from mesoderm
B.
vasculogenesis in embryo is earlier than in extraembryonic membrane
C.
endothelial channels are connected with each other in embryo and extraembryo
D.
develop primitive cardiovascular system first
E.
The cardiovascular system is one of the first functional body systems to appear within the embryo
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【多选题】Which ones are right about the book My Stroke of Luck ?
A.
It is a candid and heartfelt memoir.
B.
It is about the author's childhood, his wife, his family and the life changing event.
C.
It is only about the eighth decade of his life.
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The words in this book are touching, funny, inspiring and uplifting.
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【简答题】下面a～e是中学化学实验中常见的几种定量仪器： (a)量筒    (b)容量瓶      (c)滴定管     (d)托盘天平     (e)温度计 （1）无“0”刻度的是 (填写编号)。 （2）下列操作合理的是 (填字母) A．用25mL碱式滴定管量取20.00mLNaHCO 3 B．用托盘天平准确称量10.20克碳酸钠固体 C．用100mL量筒量取3.2mL浓硫酸 D．配制1 mol·L –1...
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【单选题】下列有关滴定管的说法错误的是：
A.
滴定时用来准确测量流出标准溶液体积的量器。
B.
管身上面刻有均匀的分度线，下端的流液口为一尖嘴，中间通过玻璃旋塞或乳胶管连接以控制滴定速度。
C.
常用的滴定管标称容量有50ml和25ml两种，最小刻度都为0.1ml，估计读数到0.02ml。
D.
滴定管有酸式滴定管、碱式滴定管及酸碱两用滴定管三种。
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【多选题】Which ones are not the right process of double taxation for the stockholders in a C corporation?
A.
Their shares are taxed when they are both bought and sold.
B.
The corporation is taxed on the profits it makes, and the owners are taxed when this profit is distributed to them.
C.
The owners of a corporation are taxed when they receive dividend payments and when they make a profit from the sale of shares.
D.
The corporation must pay taxes on any profits it makes, and the capital raised by the sale of shares is also subject to taxation.
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【单选题】下列有关滴定管的说法错误的是
A.
滴定时用来准确测量流出标准溶液体积的量器
B.
管身上面刻有均匀的分度线，下端的流液口为一尖嘴，中间通过玻璃旋塞或乳胶管链接以控制滴定速度
C.
常用的滴定管标称容量为50.00ml和25.00ml两种，最小刻度为0.1ml，估计读数到0.02m
D.
滴定管有酸式滴定管、碱式滴定管及酸碱两用滴定管三种
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【多选题】A NPN bipolar transistor works in current application condition. which ones are right for the voltage applied relation
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VB>VE
B.
VB
C.
VC>VB
D.
VC
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【多选题】About the partitioning of primordial ventricle, which ones are right( )
A.
Interventricular septum includes muscular and membranous part
B.
Membranous part is thin, while muscular part is thick
C.
bulbar ridges participate in interventricular foramen' closure
D.
interventricular foramen between the muscular inerventricular septum and endocardial cushions exists short period
E.
the membranous part of IV septum forms earlier that the muscular part
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【多选题】Which ones are right statements for a resume? ( )
A.
Resume is a brief account of your life.
B.
Resume should be short.
C.
Resume should long with all your possible information.
D.
Resume should be written with nice outlook and honesty.
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【多选题】Which ones are right?
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Generally, it is best not to interrupt students during fluency work.
B.
It is wise to let the mistake pass when students got most of his language right.
C.
If there are some common mistakes, the teacher had better correct immediately.
D.
With different teaching focus, the teacher corrects mistakes differently, immediately or not at once.
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相关题目：
【多选题】About the development of cardiovascular system, which ones are right( )
A.
derive from mesoderm
B.
vasculogenesis in embryo is earlier than in extraembryonic membrane
C.
endothelial channels are connected with each other in embryo and extraembryo
D.
develop primitive cardiovascular system first
E.
The cardiovascular system is one of the first functional body systems to appear within the embryo
查看完整题目与答案
【多选题】Which ones are right about the book My Stroke of Luck ?
A.
It is a candid and heartfelt memoir.
B.
It is about the author's childhood, his wife, his family and the life changing event.
C.
It is only about the eighth decade of his life.
D.
The words in this book are touching, funny, inspiring and uplifting.
查看完整题目与答案
【简答题】下面a～e是中学化学实验中常见的几种定量仪器： (a)量筒    (b)容量瓶      (c)滴定管     (d)托盘天平     (e)温度计 （1）无“0”刻度的是 (填写编号)。 （2）下列操作合理的是 (填字母) A．用25mL碱式滴定管量取20.00mLNaHCO 3 B．用托盘天平准确称量10.20克碳酸钠固体 C．用100mL量筒量取3.2mL浓硫酸 D．配制1 mol·L –1...
查看完整题目与答案
【单选题】下列有关滴定管的说法错误的是：
A.
滴定时用来准确测量流出标准溶液体积的量器。
B.
管身上面刻有均匀的分度线，下端的流液口为一尖嘴，中间通过玻璃旋塞或乳胶管连接以控制滴定速度。
C.
常用的滴定管标称容量有50ml和25ml两种，最小刻度都为0.1ml，估计读数到0.02ml。
D.
滴定管有酸式滴定管、碱式滴定管及酸碱两用滴定管三种。
查看完整题目与答案
【多选题】Which ones are not the right process of double taxation for the stockholders in a C corporation?
A.
Their shares are taxed when they are both bought and sold.
B.
The corporation is taxed on the profits it makes, and the owners are taxed when this profit is distributed to them.
C.
The owners of a corporation are taxed when they receive dividend payments and when they make a profit from the sale of shares.
D.
The corporation must pay taxes on any profits it makes, and the capital raised by the sale of shares is also subject to taxation.
查看完整题目与答案
【单选题】下列有关滴定管的说法错误的是
A.
滴定时用来准确测量流出标准溶液体积的量器
B.
管身上面刻有均匀的分度线，下端的流液口为一尖嘴，中间通过玻璃旋塞或乳胶管链接以控制滴定速度
C.
常用的滴定管标称容量为50.00ml和25.00ml两种，最小刻度为0.1ml，估计读数到0.02m
D.
滴定管有酸式滴定管、碱式滴定管及酸碱两用滴定管三种
查看完整题目与答案
【多选题】A NPN bipolar transistor works in current application condition. which ones are right for the voltage applied relation
A.
VB>VE
B.
VB
C.
VC>VB
D.
VC
查看完整题目与答案
【多选题】About the partitioning of primordial ventricle, which ones are right( )
A.
Interventricular septum includes muscular and membranous part
B.
Membranous part is thin, while muscular part is thick
C.
bulbar ridges participate in interventricular foramen' closure
D.
interventricular foramen between the muscular inerventricular septum and endocardial cushions exists short period
E.
the membranous part of IV septum forms earlier that the muscular part
查看完整题目与答案
【多选题】Which ones are right statements for a resume? ( )
A.
Resume is a brief account of your life.
B.
Resume should be short.
C.
Resume should long with all your possible information.
D.
Resume should be written with nice outlook and honesty.
查看完整题目与答案
【多选题】Which ones are right?
A.
Generally, it is best not to interrupt students during fluency work.
B.
It is wise to let the mistake pass when students got most of his language right.
C.
If there are some common mistakes, the teacher had better correct immediately.
D.
With different teaching focus, the teacher corrects mistakes differently, immediately or not at once.
查看完整题目与答案