根据句意和首字母提示，写出所缺单词。

1. There is n___________ in the fridge. I have to buy some.

2. Before you enter the teacher's office, you must k__________ on the door first.

3. Bill Gates is a very r_________ man in the world. He has billions of dollars.

4. Mr Gao is eighty years old, but he has some m___________ ideas.

5. Can you tell me the m___________ of the word? Sorry, you should look it up in the dictionary.

6. Yang Liwei and Zhan Tianyou are national h_________.

7. Some people are p___________ flowers in the garden.

小学阶段的儿童记忆策略包括（）。

A.复诵

B.组织

C.排列组合

D.机械加工