按要求完成下列句子。
（1）We are making a model plane. (改为一般疑问句）
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（2）The boys are sitting under the tree. (对画线部分提问）
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（3）Look out of the window. (改为否定句)
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（4）We can see some birds over there. (对画线部分提问）
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（5）The children have some apples. (改为单数句子）
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