能与无色硝酸银溶液反应，使溶液变为蓝色的金属是（）

动漫大片《田螺遗梦》是我国文化百花园中的一朵奇葩。作品取材于中国民间传说,剔除了其中带有迷信、颓废、庸俗色彩的内容,突出了中国文化和而不同的价值理念。作品制作运用了目前国际最高水准的动画电影技术,注入了国际动漫作品所特有的神幻色彩,从而使作品更具国际口味。作品多次参加国际国内动漫节和电影节,摘取了多个奖项,赢得了国内外的好评。

若椭圆的短轴为$AB$,它的一个焦点为$F_1$,则满足$△AB{F}_1$为等边三角形的椭圆的离心率是(　　)

根据短文内容，选择正确答案。

    Library of Congress (国会）is in the United States. This library is the largest library in the world. It is 3 stories high and the book shelves in it are 500 kilometers long.

    Resources

    The library has a large collection of resources like newspapers，magazines, CDs, videos and CD-ROMs. There are also many rooms for people to meet each other or listen to music. It also has a language learning center. It gets 2,000 questions a day, and some can be answered in a few minutes. Some need more time, sometimes a few months. All workers in the library use computers to help them.

    How to join

    If you are a middle school or above, then you can come to the library and fill in a form. Don't forget to bring your ID card. You must be an American and live in the United States.

    If you have time, come along to America and take a look around for yourself!