a，b在数轴上的位置如图，化简|a+b|的结果是（　　）

最佳选项。

B

    I work as a volunteer for the poor in Haiti. I decided to take my son Brain there for a week, hoping to educate(教育) him.

    Before getting out, I told Brain this trip would be tiring and hard. For the first two days, he said almost nothing. Then on the third day, when we were climbing over high rocky mountains, he turned to me and smiled, "Really hard."

    After that, a five-year-old girl, wearing a too large dress and broken shoes, followed Brain around. Later he said regretfully(遗憾地), "I wish I could speak French." I was surprised that this was from a boy. He always hated French classes.

    One day, I was interviewing(采访) a woman villager for an article. By working hard, she had learned to read and write and became part of the leadership(领导层) of the village. That really touched my heart.

    Learning her story, Brain was greatly touched. His eyes were wet and there was love and respect(尊重) on his face. He finally understood the importance of my work. When leaving for home, Brain even offered(提供) to stay in as a volunteer. This trip was very meaningful.