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。

    When I intended to tell my four-year-old niece Lisa the story Snow White write by the Grimm Brothers, my elder sister stopped me immediate and gave me another storybook. When I asked if she has told Lisa the story, she shook her head and said, “I don't think girl today should listen to this story.” I was confusing. Later, my sister explained how. In this story, Snow White does nothing to rescue herself. Instead of, she depends on others' help. My sister doesn't want her daughter to learn just to turn to others help. She wants her to learn to be brave and independence. That's why my sister doesn't want to tell herself such stories as Snow White.

设m，n是两条不同的直线，α，β，γ是三个不同的平面，给出下列四个命题：

①若m⊥α，n∥α，则m⊥n   

②若α∥β，β∥γ，m⊥α，则m⊥γ

③若m∥α，n∥α，则m∥n  

④若α⊥γ，β⊥γ，则α∥β

其中正确命题的序号是（　　）