句型转换。

1. My favourite season is spring. (就画线部分提问)

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2. I like to run in spring. (变成一般疑问句)

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3. We sing a song. (变成祈使句)

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4. Winter is my favourite season. (变成一般疑问句)

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打乱传统的按年龄编班的做法，而按学生的能力或学习成绩编班的分组形式为______。