题干

如图是通过白磷燃烧来验证质量守恒定律的实验,下列说法错误的是(     )

A:反应前锥形瓶内白磷和氧气的总质量一定等于反应后生成五氧化二磷的质量

B:白磷燃烧结束,待锥形瓶冷却后再放在天平上称量

C:若白磷过量,反应后的天平仍然保持平衡

D:瓶底的细砂起隔热作用,防止瓶底受热炸裂

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A

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Dear SJ,

    Losing a best friend is never easy.

    Your problem, is not just that you miss your best friend, it is that you feel empty and lost without her friendship.

    It takes time to get over a lost, and during that time, your mind is getting used to a new way of being. This is usually a good thing, even if it feels like a bad thing.

    Now that you are on your own, you are being forced to learn to be by yourself and to rely upon your own inner voice for guidance. I am sure that this feels strange for you, but if you can hang on for a bit longer, it may work to your advantage.

    Best friends are cool, but it is important to know the difference between missing someone and being too independent upon them.

    At your age, girls do tend to stick together and having a good boyfriend may not yet be the better choice. Your friend is leaving you, her best friend, for a boyfriend. Boyfriends are completely different from best friends. The distinction is that boyfriends come and go, while girl friends often stay in your life throughout high school, and even afterwards. It is a completely different sort of bond.

    I suggest that you take advantage of this period in your life to expand your horizons. Enjoy the freedom of having no best friend for a while, and hang with the group. By the time your former best friend breaks up with her boyfriend, you will be in a completely different place, a far better place.

    And, by the way, next time you feel empty and lost, try to write about it in a diary. In several months, you will look back and read it with curiosity about yourself. “Who was I then, and what could I have been thinking?”