连词成句。

1. mother's, is, your, when, birthday

    _____________________________

2. May's, old, how, is, sister

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3. You, a, music, do, have, Festival 

    _____________________________

4. My, fifteenth, today, birthday

    _____________________________

5. Sports, collection, like, I

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潜水艇通过改变_________实现下潜和上浮；氢气球能升空是因为氢气的密度比空气的密度________。