函数$f\left(x\right)=\frac{2x}{1+x^2}$的值域为(    )

⑴____ A. student      B. juice      C. computer

⑵____ A. rice   B. bread   C. right

⑶____ A. window   B. would   C. worker

⑷____ A. hungry   B. hand   C. have

⑸____ A. use   B. dumpling   C. mum

①当气体温度升高到t₂=127℃时,活塞升高了多少?

②当气体温度升高到t₃=357℃时,缸内气体的压强。

“黄袍加身”“杯酒释兵权”等历史典故，与下列哪个历史人物有关（　　）

    Lao she Teahouse

    It is named after the famous Chinese writer, Lao She, and one of his best-known plays, Teahouse. It has three floors. Customers here can enjoy many kinds of traditional Chinese art performances, and taste beijing-style snacks

    Location: Qianmen Xidajie, Xuanwu District

    Te:010-63036830

    Wanghaixuan Teahouse

    Though we can't see the sea at this teahouse, it's still a good place to drink tea it's a bit small but the hall is big enough. And you can enjoy the performance of the waiters

    Drink a cup of hot tea and have some fresh desserts

    Location: Deshengmen Dajie, Xicheng District

    Tel:010-64010791

    Yuansu Teahouse

    It is a quiet place. There are many kinds of popular tea leaves for you to choose. And you can notonly drink tea but also enjoy music by Chinese traditional instruments. Customers here can have a good time

    Location: Xinyuanxili Dongjie, Chaoyang District

    Te:010-64673079