根据句意，填写恰当的短语介词完成句子。

1. Look! There are some birds_____the sky.

2. I bought this coat at a shop_____our neighborhood.

3. A terrible accident happened_____him last night.

4. Lisa didn’t come to school this morning_____illness.

5. —Are you busy? 

    —Yes. I am swimming_____an ocean of paper.