Aristotle once wrote that “happiness is a state of activity”. In other words, whether you're seeking life-long satisfaction or a few moments of good cheer, you've got to move forward. We've interviewed the experts and found five steps to take toward a sunny mood（心情）：

    Over a 30-year period, University of Illinois researchers asked nearly 120, 000 people how income, education, political participation volunteer activities and close relationships affected their happiness. Reported Newsweek, s Sharon Begley on the findings, “The highest levels of happiness are found with the most stable and satisfying relationships. ”

    Singing aloud, talking to a stranger, raising your hand: all may increase a feeling of happiness, according to a study from Wake Forest University. Participants（参与者）followed the development of their moods for two weeks and reported feeling happier when they were more outgoing and less happy when reserved or withdrawn.

    The editors of forbes. Com gave $5 or $20 to 46 strangers by chance. Half the group was told to spend the money on themselves, while the other half was told to spend it on others. Those who'd shared the wealth felt much happier at the end of the day than those who'd spent it on themselves. There was no difference in happiness between those who spent $5 or $20, suggesting that it's not how much money you spend, but how you spend it, that inspires the spirit.

    Studies from the Positive Psychology Center showed that discouraged people who wrote down three good things that happened to them each day for six months reported an improved attitude.

    Drinking water really can help keep you cheerful. A small 2012 study from the University of Connecticut suggested that even slight dehydration（脱水） affected the moods of its female participants.

 2015年我国计划发射4颗北斗三期实验卫星，对全球导航中的新技术进行验证．发射卫星的火箭常用的燃料是肼（N₂H₄），反应的化学方程式为：2N₂H₄+N₂O₄3X+4H₂O，则X的化学式是（　　）