未知题型

尿路结石最常见的是以下哪种成分（）

A.尿酸盐
B.磷酸盐
C.胱氨酸盐
D.草酸钙
E.碳酸盐

【参考答案】

D
解析：尿路结石成分：草酸钙结石最常见，磷酸盐、尿酸盐、碳酸盐次之，胱氨酸结石罕见。
故答案为D项。

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问答题

The idea of the American Dream is rooted in the_____.

未知题型

People have speculated for centuries about a future without work.Today is no different ，with academics，writers，and activists once again ___1___ that technology is replacing human workers. Some imagine that the coming work-freeworld will be defined by ___2___ . A few wealthy people will own all the capital ，and the masses will struggle in animpoverished wastelanD.
A different and not mutually exclusive ___3___ holds that the future will be a wasteland of a different sort ，one ___4___by purposelessness：Without jobs to give their lives ___5___ ，people will simply become lazy and depresseD.___6___today’s unemployed don ’t seem to be having a great timE.One Gallup poll found that 20 percent of Americanswho have been unemployed for at least a year report having depression，double the rate for ___7___ Americans. Also，some research suggests that the ___8___ for rising rates of mortality，mental-health problems，and addicting___9___poorly-educated middle-aged people is shortage of well-paid jobs. Perhaps this is why many ___10___ the agonizingdullness of a jobless futurE.
But it doesn ’t ___11___ follow from findings like these that a world without work would be filled with uneasE.Such visions are based on the ___12___ of being unemployed in a society built on the concept of employment. Inthe ___13___ of work，a society designed with other ends in mind could ___14___ strikingly different circumstances for thefuture of labor and leisurE.Today，the ___15___ of work may be a bit overblown. “Many jobs are boring ，degrading，unhealthy，and a waste of human potential，” says John Danaher ，a lecturer at the National University of Irelandin Galway.
These days，because leisure time is relatively ___16___ for most workers，people use their free time tocounterbalance the intellectual and emotional ___17___ of their jobs. “When I come home from a hard day ’s work ，Ioften feel ___18___ ，” Danaher says，adding，“In a world in which I don’t have to work，I might feel ratherdifferent ”— perhaps different enough to throw himself ___19___ a hobby or a passion project with the intensity usuallyreserved for ___20___ matters.
1____
A.boasting
B.denying
C.warning
D.ensuring
2A.inequality
B.instability
C.unreliability
D.uncertainty
3A.policy
B.guideline
C.resolution
D.prediction
7A.rich
B.urban
C.educated
D.working
14A.disturb
B.restore
C.exclude
D.yield
16A.tricky
B.lengthy
C.mysterious
D.scarce
19A.off
B.against
C.behind
D.into
20A.technological
B.professional
C.educational
D.interpersonal
4A.characterized
B.divided
C.balanced
D.measured
17A.demands
B.standards
C.qualities
D.threats
5A.wisdom
B.meaning
C.glory
D.freedom
15A.model
B.practice
C.virtue
D.hardship
9A.under
B.beyond
C.alongside
D.among
18A.ignored
B.tired
C.confused
D.starved
6A.Instead
B.Indeed
C.Thus
D.Nevertheless
8A.explanation
B.requirement
C.compensation
D.substitute
13A.absence
B.height
C.face
D.course
10A.leave behind
B.make up
C.worry about
D.set aside
11A.statistically
B.occasionally
C.necessarily
D.economically
12A.chances
B.downsides
C.benefits
D.principles
请帮忙给出每个问题的正确答案和分析，谢谢！

判断题

电火花加工机床的脉冲参数可以任意调节，生产中可以通过控制极性和脉冲的长短（放电持续时间的长短）控制加工过程，因此，在一台电火花加工机床上可以连续进行粗加工、半精加工和精加工。