根据空气的成分填空：

（1）小白鼠在装有空气的密闭容器中可存活一段时间，说明空气中含有____ ；

（2）石灰水长期露置在空气中会出现白色固体物质，说明空气中含有____ ；

（3）夏天，盛放冰棒的杯子外壁上附有一层水珠，说明空气中含有____ ；

（4）灯泡中充入____ 时能发出不同颜色的光，制成多种用途的光源．

设a∈R，若函数y=e^x+2ax，x∈R有大于0的极值点，则（　　）

    Coffee is the best!

    Wake up in the morning and drink coffee. Coffee is a kind of drink. It helps you wake up and feel ready for the day.

    When you are tired but you have a lot of work to do, you can have a cup of coffee. So you can finish the work. Coffee tastes great too. You can drink coffee from Brazil (巴西) or China.

    Tea! Tea! Tea!

    Chinese tea is famous(有名的). There are many different kinds of tea like black tea, green tea and flower tea. You can drink tea from different places of China. There is Longjin tea from the West Lake in Hangzhou and Pu'er tea from Yunnan. Tea is not very expensive(贵的) but there is also very expensive tea from special places. Oolong tea from Taiwan or Fujian is very expensive.

    Hot chocolate -- the best friend in winter

    Hot chocolate is the best drink for winter days. It makes you feel warm. In summer, drink a chocolate milkshake(奶昔) with ice. It's nice and it will help you keep cool.