在下列各句的空白处填入一个适当的词，使句子意思完整，语法正确。

1. When I saw him, he was walking ________ his school.

2. All the guests arrived at the party but the host didn't ________ up.

3. On Sunday school is usually ________ and students have one day off.

4. Gold is a kind of much-loved ________, so everyone like it.

5. Yesterday Tom ________ me some money and I returned it to him today.