根据句子意思及汉语，写出空缺单词的正确形式。

1. In winter, children like making              (雪人) and              (扔) snowballs.

2. I meet an old friend of              (我的).

3. Meimei's family lives on the              (第九)floor (层)

4. We have a lot of              (趣事) in winter.

5. What              (别的) do you want to say at the meeting?

论知识结构、认知结构和教学结构的关系。