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