材料一  中国古代与世界其他国家的科技发明统计资料（据《自然科学大事年表》的统计）

材料二 《中国的世界记录》收录的中国古代科技成果统计

材料三  英国学者李约瑟博士在对中国科学技术发展进行研究后发现，16世纪前，中国的科学技术发展水平远远超过西方，除“四大发明”外，还有很多发明，如机械钟、铸铁技术、瓷器、万向架、马镫马具、独轮车，拱桥等都首创于中国。“为什么近代科学只在欧洲文明中发展，而未在中国文明中成长？”这个疑问被学术界命名为“李约瑟难题”，引起国内外学者的广泛关注。

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阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

Once there was a free bird. She floated in the sky,____(catch) worms for lunch and swam in the summer rain trickles(滴), like many ____birds. But she had a habit:____some event occurred in her life, whether good or bad, the bird would pick up a stone ____the ground to memorize it. Every day she sorted out her stones, laughed remembering joyful events, and cried remembering the sad ones.

The bird always took the stones with her, whether she was flying in the sky or walking on ____earth, and she never forgot about them. Years had passed ____the free bird got a lot of stones, but she still kept on sorting them out, remembering the past. It was becoming more and more difficult for her to fly.

The bird was unable to move on her own，____could she catch worms anymore. Only rare rain gave her the necessary energy.But the bird ____(brave) endured all the hardships, ____(guard) her precious memories. After some time the bird died of ____ (starve) and thirst.