Dear Mum,

    I have studied abroad for some time. I miss you very much now.

    I 1 learned the famous saying “You don't know what you've got until it's gone.”Yes! Mill Li said her maths teacher made a huge difference in her life. But she was 2 because she had no chance to tell her teacher. This made me think a lot, especially 3 I'm thousands of kilometers away. I'm writing to you because I want you to know how 4 I love you.

    It's said that a 5 happiness was mostly because of their childhood. That's quite right. I still remember the times when you 6 my hand as we walked along. You told me stories about the brave elephant and encouraged me to be a 7 girl. … My childhood was filled with these warm memories.

    How time flies! There have been good times and bad times, but you were always by my side. When I won a prize, you smiled and felt proud 8 me. When I failed the exam, you comforted me. You always gave me courage to 9 all my difficulties.

    You've always said that we should judge（判断）people's 10 by how they live their lives every day. I think I'm now living a happy life. Thank you, Mum.

Love,

Feifei

仿照划线句子，在下面横线上补写一句话，使之与前文构成排比。

      钻石再大，若永埋地底也只是等同于砖石；黄金再多，若久藏土中也只是等同于黄土；____，____。……世上许许多多东西，若永远不为人所用，原本珍贵的也会变得一文不值。

将下列陈述句改成反问句

①那奔驰的列车正是我们祖国奋勇前进的象征。

②都是你自己找的，我帮不得了你的忙。

细胞是生物体结构和功能的基本单位。下面是几种细胞的模式图，请据图回答问题。

关于惯性，下列说法中正确的是（   ）