1. The lava / flew overhead. / when we / was pouring out/

  → The lava was pouring out when we flew overhead.

2. friendly / and the weather / The people / sunny. / is / are /

  → The people are friendly and the weather is sunny. 

3. must take / starting position. / Each runner / to the / a bottle of water / and return /

  → Each runner must take a bottle of water and return to the starting position.

4. in / each team / participate / this event. / Six people / from /

  → Six people from each team participate in this event.

5. is based on / in this poem. / of Saint Nicolas / Santa Claus / the description /

  → Santa Claus is based on the description of Saint Nicholas in this poem.

6. are / at Tet. / traditional / Marigolds /

  → Marigolds are traditional at Tet.

=>

1. The lava was pouring out when we flew overhead.

2. The people are friendly and the weather is sunny.

3. Each runner must take a bottle of water and return to the starting position.

4. Six people from each team participate in this event.

5. Santa Claus is based on the description of Saint Nicholas in this poem.

6. Marigolds are traditional at Tet.