根据句意及所给中文提示或英文解释，写出句中所缺单词，每空限填一个单词。
People like travelling in ____ (春天) because it is neither too hot nor too cold.
—What's your father's ____  (职业)?—He is a doctor.
The 30^th Olympic Games will be held in London, the ____ (首都) of England.
Lucy is polite and ____ (乐于助人的). We all like her.
Our maths teacher asked you to go to his office____  (立即). He is waiting for you.
Colours can change our moods and some may make us feel ____ _ (in need of sleep).
Hurry up, or we can't____  (arrive at) the railway station on time.

阅读下列材料，回答问题。

材料一：

材料二：“这是预兆资产阶级社会到来的三大发明。……把骑士阶层炸得粉碎，……打开了世界市场并建立了殖民地，……却变为新教的工具，并且一般地说变为科学复兴的手段，变成创新精神发展的必要前提的最重要的推动力。”

――马克思

请回答：

已知非负实数x，y满足 ，则非负实数x+y满足的最大值为____．