如图是一种航天器能量储存系统原理示意图．其中装置Y为氢氧燃料电池，下列说法正确的是（　　）

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    Sally Seaman is an American Writer. She tells young students some smart ways to make friends. In her ____, founding(建立) friendship is just like planting a tree. You should plant the seed(种子) and take care of it to make it grow.

    Firstly, you should choose a friend. A good friend should be kind and patient(有耐心的). For example, if something bad happens to you, a good friend could listen to you. And he or she should ____to help you. 

    ____, you can't be too shy. You should often ____with your friend. You should share your lives with your friend. 

    However, even best friends have fights. What should you do when you ____with your friend? You won't talk to him or her. That's ____. If so, you won't be friends ____. You need to keep on talking to him or her ____. If he or she doesn't want to talk, you can write a letter. That works.

我国实施可持续发展的核心是(　　)