When do I need 的?

Question

Why do I need 的 for 爸爸 but not for 爸 ? > me: So if I said "your father is....", it would be 你的爸是.... > me: Right? > friend: No 的 if you use 爸 > friend: we say 你爸是。。。 > friend: Or 你的爸爸是。。。。

Answer 1

“的” functions as structural particle and modal particle in Chinese. I would like to answer the question from the perspective of relationship between the attributive and noun．You will figure out when you need “的”.

 1. When a noun or pronoun is used as an attribute to show possession, the particle “的” is added.

Eg,   老师的词典 teacher’s dictionary       爸爸的车  dad’s car   学校的图书馆school library

        我的书 my book                               你的包 your bag        我们的房子our house

If a noun or pronoun is used as an attribute to describe an obvious or close relationship or modify the noun, the particle “的” is not necessary.

      我的爸爸=我爸爸 my dad     我的家=我家 my home 

我们的学校=我们学校 our school   我们的老师=我们老师 our teacher

       中文书 Chinese book                   北京地图    Beijing map         

2. When an adjectival phrase (very+adj.) or  two-syllable adjective is used as attribute, the particle “的” is needed.

Eg,     很好的成绩   very good grade      很老的房子  very old house       

         友好的同学  friendly classmates    美丽的地方   beautiful place

If   monosyllabic adjective is used as attribute, particle “的” is not necessary.

Eg, 他取得了好成绩。He got good grade.

       这是一栋老房子。This is an old house.

If you add “的”, it has a comparative meaning.

好的书可以使我们终身受益，坏的书贻害无穷。Good books benefit us for life, while bad books can cause endless harm.

In oral Chinese, 爸爸and 爸don’t have difference in meaning. One syllable just is omitted.  

Based on rule 1 I mentioned above, 你的爸爸=你爸爸.  “的” is not necessary. 你爸 is the simplified way of 你爸爸. 你的爸 doesn't exist.

Based on rule 2, when you use adjective as attribute, “的” is needed. eg, 亲爱的爸爸(dear dad).

Hope it help you guys have a better understanding of “的”. These basic rules may help you figure out when “的”   is needed and when it’s not necessary.

Answer 2

爸爸and 爸 are usually used in oral speaking.In daily life, when children called their father they would use 爸爸，when they grow up they are tending to use 爸. For example :

1.爸，我想吃鱼。

2.爸爸，我想吃冰激凌。

my father:我爸 or 我爸爸 or 我的爸爸(not very common)

your father:你爸 or你爸爸 or 你的爸爸（not very common)