one vs ones

• I'd like to buy a melon. 
• How about this one?
  
  
• I also like some oranges
• How about these big ones? 

1. 앞사 말한 명사를 다시 말할 대 명사 대신 one 또는 ones를 쓸 수 있다.
   한 사람 또는 한 개의 사물을 말할 때는 one을 쓴다.
   Which boy is your son? The one in a white shirt. 
   You should take a taxi. Where can I catch one?
   There are so many dogs. Which one is yours?
   
   둘 이상의 사람 또는 사물을 말할 때는 ones를 쓴다.
   Can you bring me my glasses? They are the ones on the desk. 
   Adam can speak four languages. Really? Which ones?
   I want to be a cheerleader. The ones at my school are very popular.
   
   
2. one과 ones 앞에 형용사를 함께 쓸 수 있다.
   a(n)/ the+ 형용사+ one
   That is a famous building. It looks like an old one.  
   All of these ties are nice, but I think I'll buy the blue one. 
   
   
3. some/ the + 형용사+ ones
   Let's go see a movie. There are some good ones in the theater.  몇몇 좋은 것들이 상영되고 있다. 
   The small envelopes are $2, and the large ones are $3. 
   
   
   
4. What do you think of these pants? I prefer the black ones. 
5. Do you have any brown boots? No, we don't. But we have some black ones.