光敏电阻R相当于控制电路中的____ （选填“开关”或“用电器”）。

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