The use of 是, 在 and 有 and the definiteness of nouns
Each of this words 是, 在 and 有 has more than one usage in Chinese. In this chapter, the focus is on sentences using these three words whose English counterparts all involve the copula verb ‘be’. Because of this similarity in English, it is important to examine and compare these three types of sentences in Chinese.

1. The basic function of 是, 在 and 有

是 (shì)

identification

我爸爸是老师。
Wǒ bàba shì lǎoshī.
My father is a teacher.

在 (zài)

location

你家在哪里?
Nǐ jiā zài nǎli?
Where is your house?

有 (yǒu)

1) possession
2) existence

1) 我有一辆自行车。
Wǒ yǒu yí liàng zìxíngchē.
I have a bicycle.
2) 桌上有一本书。

(a) 是 identification
是 is used to identify the subject.
昨天是我的生日。
Zuótiān shì wǒ de shēngrì.
Yesterday was my birthday.

(b) 在 location
在 is used to indicate where the subject is located. What follows 在 is a word or phrase indicating a location.
我家在学校对面。
Wǒ jiā zài xuéxiào duìmiàn.
My house is across from the school.

(c) 有 (possession/existence)
有 is used to indicate possession (to have; to own) or existence (there is/are).
Possession: 我有自行车,他没有。
Wǒ yǒu zìxíngchē, tā méiyǒu.
I have a bicycle, he does not (have one).
Existence: 教师(里)有三十把椅子。
Jiàoshì (li) yǒu sānshí bǎ yǐzi.
There are thirty chairs in the classroom.
Zhuō shàng yǒu yì běn shū.
There is a book on the desk.