拉伸试验试样标准中,若试样按截面形状定义的试样号为R,则表示该试样形状为()试样。

题型:单项选择题

问题:

拉伸试验试样标准中,若试样按截面形状定义的试样号为R,则表示该试样形状为()试样。

A.矩形

B.异型

C.圆形

考点:物理性能检验工初级物理性能检验工初级物理性能检验工题库
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一质点沿直线AB运动,先以速度v从A运动到B,接着以2v沿原路返回到A,已知AB间距为x,求质点在整个运动过程中的平均速度和平均速率.

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关于真菌性角膜溃疡的病原学描述,不正确的是()

A.患者多有植物性外伤史

B.镰刀菌和曲霉菌是常见的致病菌

C.长期使用糖皮质激素造成眼表免疫环境改变是重要诱因

D.抗生素的长期使用造成菌群失调也是诱发真菌感染的危险因素

E.在免疫低下人群中,烟曲霉素引起的感染最为常见

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High school dropouts earn an average of $9,000 less per year than graduates. Now a new study dispels a common belief why they quit. It’s much more basic than flunking out.
Society tends to think of high school dropouts as kids who just can’t cut it. They are lazy, and perhaps not too bright. So researchers were surprised when they asked more than 450 kids who quit school about why they left.
"The vast majority actually had passing grades and they were confident that they could have graduated from high school. " John Bridgeland, the executive researcher said. About 1million teens leave school each year. Only about half of African American and Hispanic student will receive a diploma, and actually all dropouts come to regret their decision. So, if failing grades don’t explain why these kids quit, what does Again, John Bridgeland: "The most dependable finding was that they were bored. " "They found classes uninteresting; they weren’t inspired or motivated. They didn’t see any direct connection between what they were learning in the classroom to their own lives, or to their career aspirations. "
The study found that most teens who do drop out wait until they turn sixteen, which happens to be the age at which most states allow students to quit. In the US, only one state, New Mexico, has a law requiring teenagers to stay in high school until they graduate. Only four states: California, Tennessee, Texas and Utah, plus the District of Columbia, require school attendance until age 18, no exceptions, another researcher, says raising the compulsory attendance age may be one way to keep more kids in school.
"As these dropouts look hack, they realize they’ve made a mistake. And anything that sort of gives these people an extra push to stick it out and it through to the end, is probably helpful measure. "
New Hampshire may be the next state to raise its school attendance age to 18. But critics say that forcing the students unwilling to continue their studies to stay in school misses the point—the need for reform. It’s been called for to reinvent high school education to make it more challenging and relevant, and to ensure that kids who do stick it out receive a diploma that actually means something.

According to the passage, which state has a law requiring school attendance until they graduate

A.New Hampshire
B.Utah
C.New Mexico
D.The District of Columbia

题型:单项选择题

关于人和动物的代谢叙述正确的是()

A.人和动物体所需要的能量都是由糖类供给的

B.人体内并非只有肝脏和肌肉能够合成糖元

C.人体细胞内合成蛋白质所需的必需氨基酸一定都来自食物的消化和吸收

D.在一般情况下,糖类可以大量转化成脂肪,同样,脂肪也可以大量转化成糖类

题型:单项选择题

在我国,设立拍卖企业的最低注册资本额为( )万元。

A.1
B.10
C.100
D.1 000

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