提高碱性耐火材料的抗水化性,通常采用的方法是()A.提高烧成温度使其死烧。 B.使C

题型:单项选择题

问题:

提高碱性耐火材料的抗水化性,通常采用的方法是()

A.提高烧成温度使其死烧。

B.使CaO、MgO等生成稳定的化合物。

C.加保护层减少与大气接触。

D.A、B和C。

考点:火法冶炼工火法冶炼工题库
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1,
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9
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16
,a,…按这一列数中的规律,a应该等于______.
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在一连串连续发生的原因中,有一项新的独立的原因介入,导致损失,那么对赔偿责任的承担的论述中,正确的是( )。

A.如果原一连串风险都不是被保风险,保险人不赔

B.如果原一连串风险都不是被保风险,独立介入的风险是被保风险,保险人也不赔偿

C.独立介入的风险是被保风险,保险人就赔偿

D.如果原一连串风险都是被保风险,独立介入的风险不是被保风险,保险人不赔偿

题型:单项选择题

下列商业网络组织形式中,能反映现代商业发展潮流的是[ ]

A、货郎担、大篷车

B、电子商务、网上购物、无人自动售货

C、专业化超市、连锁店

D、商业步行街、休闲购物广场

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The Book of Life

So far,scientists have named about 1.8 million living species(物种),and that’s just a small number of what probably exists on Earth.With so many plants,animals,and other living things covering the planet,it can be tough to figure out what type of grass is growing by the roadside or what kind of bird just flew by.

A soon-to-be-started Web site might help.An international team of researchers has announced the creation of Web-based Encyclopedia(百科全书) of Life(EoL).The project aims to list every species on Earth in a single,easy-to-use reference guide.

To get the encyclopedia started,the creators will use information from scientific databases(数据库) that already exist.And eventually,in special sections of the site,non-scientists with specialized knowledge will come to help.Bird-watchers,for example,will be able to input what birds they’ve seen and where.To make sure the encyclopedia is accurate,scientists will review much of the information added to it.

As the EoL develops,you might find it useful for school projects.The site will feature(以……为特色)_____special pages for kids who are studying ecosystems in their neighborhoods.Another convenient feature of the EoL is that you’ll be able to pick the level of detail you want to see to match your interests,age,and knowledge.

It now takes years for scientists to collect all the data they need to describe and analyze species.The creators of the Encyclopedia of Life hope that their new fool will speed up that process.

小题1:The Web based EoL aims to _______.

A.find out what covers the earth

B.list all living things on Earth

C.work out the number of birds

D.save the existing plants小题2:One characteristic of the EoL is that _______.

A.it is run by school students

B.it focuses on different types of grass

C.it provides different levels of information

D.it allows non-scientists to review its data小题3:In the last paragraph,“that process”means _______.

A.analyzing species

B.creating a new tool

C.collecting data

D.describing species

题型:单项选择题

小明为粗略测定某电风扇正常工作时电能转化为机械能的效率,利用一个铭牌上标有额定电压为U,但其它字迹不清的小型直流电风扇来进行实验,实验操作过科及记录数据如下:A.按如图所示的电路图连接电路,其中M为电风扇;B.闭合开关,叶片转动,移动变阻器的滑片,直至叶片刚好不转动,记录此时电压表、电流表的示数分别为U1,I1;C.调节滑动变阻器的滑片,使其两端电压为U,让电风扇处于正常工作状态.记录此时电流表的示数为I.请你根据小明的实验记录,回答下列问题:

(1)该电风扇线圈导体的电阻为_________

(2)若不计叶片转动时所受摩擦,则电风扇正常工作时电能转化为机械能的效率为η= _________ (用测得的己知量表示).

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