文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号（ ），并在其下面写出该加的词。

删除：把多余的词用斜线（ ）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词；

2）只允许修改10处，多者（从第11处起）不计分。

    I couldn't believe my ears when I heard my name calling. I was chosen to play the leading role in Cinderella, that was my dream. As a shy and thin girl, I used to be quite afraid of speaking in the public. But my parents and teachers always encourage me to do so. Now I have changed great. In class, I am often the first one to stand back and answer questions even if I may make some mistakes. No pains, no gains. Now I am always brave enough overcome the difficulty in my heart and have changed in a lively girl. So my experience shows that we should not be afraid of losing face but only in this way can we make progresses.

在0到20的自然数中，立方根是有理数的共有（　　）

“绿叶在光下合成淀粉”的实验中，把叶片放入酒精中并隔水加热的目的是（    ）