高压给水泵为什么不能在规定的最小流量以下运行?

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问题:

高压给水泵为什么不能在规定的最小流量以下运行?

考点:汽轮机检修汽轮机运行与检修汽轮机运行与检修题库
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     In 1826, a Frenchman named Niepce needed pictures for his business. But he was not a good artist,

so he invented a very simple camera. He put it in a window of his house and took a picture of his garden.

That was the first photo.

     The  next  important  date  in  the  history of photography (摄影) was in 1837. That year, Daguerre,

another Frenchman, took a picture of his reading room. He used a  new  kind  of  camera in a different

way. In his picture you could see everything very clearly, even the smallest thing. This kind of photo was

called Daguerreotype.

     Soon, other people began to use Daguerre's way. Travelers brought back wonderful photos from all

around the world. People took pictures of famous buildings, cities and mountains.

     In about 1840, photography was developed. Then photographers could take pictures of people and

moving things. That was not simple. The photographers had to carry a lot of  film  and  other  machines.

But this did not stop them, for example, some in the United States worked so hard. Mathew Brady was

a famous American photographer. He took many pictures of great people. The pictures were unusual

because they were very lifelike (栩栩如生的).

     Photography also became a kind of art by the end of the 19th century. Some photos were not just

copies of the real world. They showed ideas and feelings, like other art forms.

1. Who took the first photo?

   __________________

2. The Daguerreotype was a kind of photo, wasn't it?

   __________________

3. If a photographer wanted to take pictures of moving things in 1840, what did he have to do?

   __________________

4. Why was Mathew Brady famous?

   __________________

5. When did photography become a kind of art?

   __________________

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将下列各种动物的行为与其所属的类型连接起来.

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投资大、运行管理复杂,管网要有较高的自动控制措施的热网是()。

A.枝状管网

B.直线管网

C.环状管网

D.辐射管网

题型:问答题 简答题

油管头安装于采油树和套管头之间,其上法兰平面为计算()和井深数据的基准面。

A、油管补距

B、套管补距

C、套管深度

D、油管深度

题型:问答题 简答题

关于新生儿感染性肺炎的病原体,叙述错误的是()

A.产前感染常见病原体为巨细胞病毒、弓形体、大肠埃希菌等

B.产时感染常见病原体为大肠埃希菌、肺炎球菌、克雷白杆菌等

C.产后感染常见病原体为金黄色葡萄球菌、大肠埃希菌、克雷伯杆菌等

D.衣原体肺炎主要病原体是肺炎衣原体

E.β-溶血性链球菌感染也常见

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