Here are the correct forms of the words for each sentence:

1. He didn’t win the championship, so he felt very **hopeless**. (hope)
2. Because of his **laziness**, they failed the exam. (lazy)
3. Vinamilk company has served customers a lot of **products** recently. (produce)
4. Tet holiday is one of the most important **celebrations** for Vietnamese people. (celebrate)
5. Laura loves all of Vietnamese dishes, **especially** Nem. (special)