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.
