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【单选题】
作用在刚体上,互不平行三于一点,刚体() 状态。
A.
一定处于平衡
B.
处于不平衡
C.
运动状态
D.
可能处于平衡
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【简答题】Li Wei: You know, my school is quite different. Sophie: Really? ? Li Wei: We have our in a factory. Sophie: What do you usually do there? Li Wei: We how to use the machines. Sophie: That’s .
【简答题】We have to do quite a bit of reading, and then we have our________(手头) work which would be an essay. )
【简答题】Text 3 (1’×7=7’)Janet: So what does the world of high ________ have to do with our website?Joe: Well, I thought we could do something on the Bank of England Museum — It’s really quite interesting.
【简答题】(8分)合理利用资源是当今社会关注的热点。 (1)明矾净水,是因为明矾溶于水生成的胶状物, 悬浮于水中的杂质,使水澄清;新型自来水消毒剂ClO 2 可由含钠元素的盐X发生下列反应制取: Cl 2 +2X=2NaCl+2ClO 2 ,则X的化学式为 。 (2)煤燃烧产生的废气里,因含 (填名称),造成酸雨中含硫酸。 (3)煤的气化是一种重要的煤炭资源综合利用技术,其过程如图I所示。合成气中的物质A和...
【单选题】听力原文:M: I have a terrible cold. W: We have quite a few medications to make you more comfortable. What does the woman probably do?
A.
A teacher.
B.
A student.
C.
A doctor.
【单选题】We are quite confident we do have the capacity to ()more advanced machines for our country.
A.
decrease
B.
protest
C.
decline
D.
produce
【简答题】(7分)明矾[化学式为KAl(SO 4 ) 2 ·12H 2 O]是一种常用的净水剂。小华同学为了探究明矾的净水原理,进行了如下实验探究: 【提出问题】明矾为什么能够净水? 【查阅资料】材料一:净水原理是,净水剂具有较大表面积或者净水剂粒子与水反应生成表面积较大的物质,把水中的细小漂浮颗粒吸附到表面,使其密度加大并下沉。 材料二:明矾[KAl(SO 4 ) 2 ·12H 2 O]在水溶液中可以解离...
【简答题】Now, this way of working isn't easy, but as I said, it's more and more the way many of us have to work, so we have to understand it. And I would argue that it's especially needed for work that's compl...
【单选题】下列说法正确的是(  )
A.
水晶、玛瑙的主要成分是二氧化硅
B.
明矾、漂白粉、臭氧的净水原理相同
C.
煤的干馏和石油的分馏都属于物理变化
D.
亚硝酸钠是一种食品防腐剂,使用时其用量可以不加限制
【单选题】明矾是一种净水剂,明矾净水的原理是( )
A.
Al 3 + 有较强的吸附性
B.
Al 3 + 与悬浮物生成沉淀
C.
Al 3 + 与水反应生成的氢氧化铝胶体具有吸附性
D.
明矾难溶于水
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