阅读下面短文，从每小题所给的A、B、C三个选项中，选出可以填入空白处的最佳答案。
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
