花色组织是通过什么方式形成的？

Reading comprehension.

     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.

Answer the following questions according to what you read.

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? 

    ____________________________________________________________________________

“负数小于O”的题设是______，结论是______；写成“如果…那么…”的形式是______，这是一个______命题．

社区设立小区业主委员会和小区活动中心等体现了社区的哪项功能（）

A.社会化功能

B.生产、消费及分配的功能

C.社会参与和归属的功能

D.社会控制功能

E.相互支持及福利功能

在关系数据模型中，一个关系中的主码【 】。

A．可以取值为NULL(空值)

B．只能是单个属性

C．不能是其他关系的外码

D．只能有一个