Sure, here are the correct forms of the words along with explanations:

1. **lovely** - She’s beautiful with a **lovely** smile. (The adjective "lovely" describes the smile.)
2. **Unluckily** - **Unluckily**, the barber cut my hair too short. (The adverb "unluckily" describes the unfortunate event.)
3. **different** - Each of my friends has a **different** character. (The adjective "different" describes the character.)
4. **sociable** - Nam is very **sociable**, kind and generous. (The adjective "sociable" describes Nam's personality.)
5. **orphanage** - My uncle often spends his free time doing volunteer work at a local **orphanage**. (The noun "orphanage" is the place where orphans live.)
6. **curly** - She has short **curly** hair. (The adjective "curly" describes the hair.)
7. **action** - Trung and his brother like **action** movies very much. (The adjective "action" describes the type of movies.)
8. **activities** - My brother likes acting and outdoor **activities**. (The noun "activities" refers to things he likes to do.)
9. **speech** - Bell experimented with ways of transmitting **speech** over a long distance. (The noun "speech" refers to spoken words.)
10. **successfully** - Bell **successfully** demonstrated his invention. (The adverb "successfully" describes how he demonstrated it.)
11. **arrangement** - Mr. Phong made an **arrangement** to see us at two o’clock. (The noun "arrangement" refers to the plan made.)
12. **assistant** - Thomas Watson was Bell’s **assistant**, wasn’t he? (The noun "assistant" refers to the person who helps.)
13. **electricity** - There wasn’t any **electricity** in our village two years ago. (The noun "electricity" refers to the power supply.)
14. **traditional** - “The lost shoe” is one of the **traditional** stories I like best. (The adjective "traditional" describes the type of story.)
15. **excited** - Everyone was **excited** at the soccer match. (The adjective "excited" describes the feeling of the people.)
16. **inventor** - Marconi was the **inventor** of radio. (The noun "inventor" refers to the person who invented the radio.)
17. **invention** - The **invention** of radio was made by Marconi. (The noun "invention" refers to the creation of the radio.)
18. **successfully** - Alexander G.B **successfully** demonstrates his invention. (The adverb "successfully" describes how he demonstrates it.)
19. **arrangement** - Can I leave the **arrangement** of the table for you? (The noun "arrangement" refers to the act of setting up the table.)
20. **deliveries** - We have two postal **deliveries** each day. (The noun "deliveries" refers to the act of delivering mail.)

These forms are chosen based on the grammatical context and the meaning intended in each sentence.