如何根据机械的负荷和转速选用合适粘度的机械油?

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问题:

如何根据机械的负荷和转速选用合适粘度的机械油?

考点:延迟焦化操作工考试延迟焦化操作工考试题库
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物质在水中可能存在电离平衡、盐的水解平衡和沉淀的溶解平衡,它们都可看作化学平衡。请根据所学知识回答:

(1)A为0.1 mol·L-1的(NH4)2SO4溶液,在该溶液中各种离子浓度由大到小的顺序为       

(2)B为0.1 mol·L-1 NaHCO3溶液,实验测得NaHCO3溶液的pH>7,请分析NaHCO3溶液显碱性的原因:                                                            

(3)C为FeCl3溶液,实验室中配制FeCl3溶液时通常需要向其中加入       ,目的是                                                     

若把B和C溶液混合,将产生红褐色沉淀和无色气体,该反应的离子方程式为                                               

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_____ in the classroom are the people who are attending the parents' meeting. [ ]

A. Seating    

B. Seated      

C. To sit  

D. Having seated

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在调节放松状态下,平行光线经眼屈光系统后聚焦在视网膜后,这种屈光状态为

A.弱视

B.正视

C.近视

D.散光

E.远视

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若期货交易保证金为合约金额的5%,则期货交易者可以控制的合约资产为所投资金融的()倍。

A.5 

B.10 

C.15 

D.20

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Washington, DC has traditionally been an unbalanced city when it comes to the life of the mind. It has great national monuments, from the Smithsonian museums to the Library of Congress. But day-to-day cultural life can be thin. It attracts some of the country’s best brains. But far too much of the city’s intellectual life is devoted to the minutiae of the political process. Dinner table conversation can all too easily turn to budget reconciliation or social security.

This is changing. On October 1st the Shakespeare Theatre Company opened a 775-seat new theatre in the heart of downtown. Sidney Harman hall not only provides a new stage for a theatre company that has hitherto had to make do with the 450-seat Lansburgh Theatre around the corner. It will also provide a platform for many smaller arts companies.

The fact that so many of these outfits are queuing up to perform is testimony to Washington’s cultural vitality. The recently-expanded Kennedy Centre is by some measures the busiest performing arts complex. But it still has a growing number of arts groups which are desperate for mid-sized space down- town. Michael Kahn, the theatre company’s artistic director, jokes that, despite Washington’s aversion (厌恶) to keeping secrets, it has made a pretty good job of keeping quiet about its artistic life. The Harman Centre should act as a whistle blower.

Washington still bows the knee to New York and Chicago when it comes to culture. But it has a good claim to be America’s intellectual capital. It has the greatest collection of think-tanks on the planet, and it regularly sucks in a giant share of the country’s best brains. Washington is second only to San Francisco for the proportion of residents twenty-five years and older with a bachelor’s degree or higher.

Washington’s intellectual life has been supercharged during the Bush years, despite the Decider’s aversion to ideas. September 11th, 2001, put questions of global strategy at the center of the national debate. Most of America’s intellectual centers are firmly in the grip of the left-liberal establishment. For all their talk of "diversity" American universities are allergic to a diversity of ideas. Washington is one of the few cities where conservatives regularly do battle with liberals. It is also the center of a fierce debate about the future direction of conservatism.

The danger for Washington is that this intellectual and cultural renaissance will leave the majority of the citizens untouched. The capital remains a city deeply divided between over-educated white itinerants and under- educated black locals. Still, the new Shakespeare theatre is part of job-generating downtown revival. Twenty years ago downtown was a desert of dilapidated(破旧的) buildings and bag people. Today it is bustling with life. If Washington is struggling to fix the world, at least it is making a reasonable job of fixing itself.

According to the text, which of the following statements is correct()

A. sidney Harman hall provides a new stage for Shakespeare Theatre Company

B. michael Kahn is the artistic director of the expanded Kennedy Centre

C. lansburgh Theatre is in the heart of downtown area in Washington

D. many smaller arts groups are desperate for mid-sized space downtown

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