在用单杠杆差压变送器测量锅炉水位时,为使变送器投人工作,其正确的操作顺序为() A.

题型:单项选择题

问题:

在用单杠杆差压变送器测量锅炉水位时,为使变送器投人工作,其正确的操作顺序为()

A.先开测量水位和参考水位管截止阀,再开平衡阀,最后关闭截止阀

B.先关平衡阀,再开截止阀,最后再开平衡阀

C.先开平衡阀,再开截止阀,最后再关平衡阀

D.先开平衡阀,再开截止阀,最后再关截止阀

考点:自动控制原理自动控制原理题库
题型:单项选择题

用NA表示阿伏加德罗常数,下列叙述不正确的是(  )

A.标准状况下,22.4L H2含有的分子数为1 NA

B.常温常压下,1.06g Na2CO3含有的Na+离子数为0.02 NA

C.常温常压下,48g O3所含的氧原子数为3NA

D.物质的量浓度为0.5mol/L的MgCl2溶液中,含有Cl-个数为1 NA

题型:单项选择题

The Chinese invented paper in 105 A. D. They mixed the bark of a tree and rags (破布) with water, put a screen into the mixture, and lifted out a thin piece of wet paper. They dried the paper in the sun.

The Chinese kept their secret of how to make paper until a war with Muslims in the ninth century. The art of papermaking soon spread throughout the Muslim world.

The Mayan Indians in Central America and Pacific Islanders also discovered how to make paper, but their knowledge never spread to the rest of the world.

For centuries, all paper was made by hand. Rags were the main material. Then a French scientist discovered that people could make paper from wood, too. Finally, in the eighteenth century. a Frenchman invented a machine to make paper from wood.

小题1:Who discovered how to make paper?

A.The Chinese.

B.The Pacific Islanders.

C.The Mayan Indians.

D.All of the above.小题2: When did the Chinese invent paper according to the passage?

A.About 1 ,800 years ago.

B.About 1, 900 years ago.

C.About 2, 000 years ago.

D.About 2, 100 years ago.小题3: How was papermaking introduced into the rest of the world from China?

A.Through wars.

B.Through the Muslims.

C.Through the Mayan Indians.

D.Through the Pacific Islanders.小题4:Which of the following is the best title for this passage?

A.The Invention of Paper.

B.The History of Papermaking.

C.Different Ways of Making Paper.

D.The Invention of a Papermaking Machine.

题型:单项选择题

慢性肺心病肺动脉高压形成的最主要原因是()

A.肺气肿压迫及肺泡壁破坏使肺毛细血管床减少

B.肺小动脉炎

C.血液粘稠度增加

D.缺氧引起肺小动脉痉挛

E.血容量增加

题型:单项选择题

企业、事业单位建立的各项最高计量标准,须向()部门申请考核。

A.省级人民政府计量行政部门

B.县级人民政府计量行政部门

C.与其主管部门同级的人民政府计量行政部门

题型:单项选择题

对于过节叙述不正确的是()

A、过春节一般要穿新衣服,亲戚、朋友、熟人、同学之间见面,要互致问候,态度要热情欢快,有时还要说一些吉利话,平时可话的玩笑话这时不可随便说,走亲访友,一般都要略备礼品

B、清明来临,学校一般要组织祭扫烈士墓,缅怀先烈的活动,祭扫过程中,要服饰庄重,不要穿花花绿绿的与庄严气氛不协调的衣服;态度要严肃,语调要沉重,不可嬉笑打闹;要遵守纪律,按统一口令向烈士鞠躬行礼,瞻仰和参观烈士墓事迹要保持安静

C、在过重阳节时我们都要喝菊花茶,吃棕子

D、中秋节要注意问候长辈,元旦、国庆等节日要注意布置环境,参加庆祝活动等

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