The most common use of 是 is the copula, which connects nouns, noun phrases, and/or pronouns. 是 functions as a verb, and like all other Chinese verbs, is not conjugated for person, number, or tense.
是
shì
to be
她是中国人 ◦
tā shì Zhōngguó rén.
She is Chinese.
是在北京 ◦
shì zài Běijīng.
It's in Beijing.
不是在北京 ◦
bù shì zài Běijīng.
It's not in Bejing.
不是现在 ◦
bù shì xiàn zài
(it is) not now
是八点钟 ◦
shìbā diăn zhōng
(it is) at eight o'clock
钱是给你的 ◦
qián shì gěi nĭ de.
The money is for you.
三加三是多少 ?
sān jiā sān shì duōshăo?
How much is three plus three?
哪条是学院路 ?
nă tiáo shì Xuéyuàn lù?
Which one (which road) is College road?
Another very important verb is 有, which means "to have." To negate any verb, including adjectival stative verbs, the negation particle 不 is placed before the verb. 有 is the only exception; it is negated with 没 instead of 不.
有
yŏu
to have
他有百美金 ◦
tā yŏu băi měi jīn.
He has 100 dollars.
她没有时间 ◦
tā méi yŏu shíjiān.
She doesn’t have time.
他家里有六个人 ◦
tā jiālĭ yŏu liù gè rén.
There are six people in his family.
At this point it essential to note that 有 (yŏu) and 是 (shì) are not interchangeable, even in negative form.
Positive
Negative
是 (shì: is)
不是 (Bùshì: is not)
有 (yŏu: have)
没有 (Méiyǒu: not have)
没有 is interchangeable with 没 except in the question word 有没有 ("have-not-have"), which means "do(es) X have," where X is any noun or pronoun.
