When I was in the ____ (九) grade, luckily, I was chosen to be the princess in the school play. For weeks my mother had helped me practice my lines. But ____ (一旦) on the stage, every word disappeared from my head. Then my teacher asked me to change my role to be a narrator (解说者) for the play.

    ____ (尽管) I didn't tell my mother what had happened that day, she noticed my unhappiness. She asked if I wanted to take a walk in the garden.

    It was a lovely spring day. We could see several dandelions (蒲公英) ____ (在…中间) the grass. I watched my mother bend down by one of the dandelions. "I think I'll dig up all these weeds (野草)," she said. "From now on, we'll only have roses in this garden."

    "But I like dandelions," I disagreed. "All flowers are beautiful-even dandelions!"

    My mother looked ____ (严肃地) at me. "Yes, every flower gives pleasure in its ____ (自己的) way, doesn't it?" she asked thoughtfully. I nodded. "And that is true of people, too," she added.

    When I ____(意识到) that she had guessed my pain, I started to cry and told her the ____ (真相). "But you will be a wonderful narrator," she said, reminding me of how much I loved to read stories aloud.

    Thanks to my mother's encouragement, I got to know everybody had his or her ____ (价值) in the world. I felt ____ (骄傲的) of the role in the play.

风速廓线是风速随高度的变化曲线。风速通常随离地面高度增大而增加。达到一定高度后，地面的摩擦影响可忽略不计，该高度称为梯度风高度。下图为不同粗糙度情况下的风廓线比较示意图，据此完成以下问题。