What is 是?

是 (shì) - To Be

是 (shì) is one of the most fundamental and frequently used verbs in Mandarin Chinese. It primarily means "to be" and is used to link two nouns or pronouns, indicating that they are equivalent or that one defines the other.

Key Functions:

• Equivalence/Identification: It connects two nouns or pronouns to show that they are the same. For example, "我 是 学生 (wǒ shì xuésheng)" - "I am a student". This uses 是 to identify "I" as a "student". See more about Equivalence and Identification.

• Linking Nouns/Pronouns with Descriptive Phrases: It can connect a noun/pronoun with a descriptive phrase containing an adjective or noun. For instance, "今天 是 星期一 (jīntiān shì xīngqíyī)" - "Today is Monday". This uses 是 to state that today is a Monday. More on Linking Nouns and Descriptive Phrases.

• Affirmative Responses: It can be used as an affirmative response, similar to "yes" in English. This is generally more formal than using 嗯 (en) or 对 (duì). To read more about Affirmative Responses.

Important Considerations:

• Cannot be used to link nouns with verbs or adjectives directly. Unlike English, you cannot say "我 是 累 (wǒ shì lèi)" meaning "I am tired". Instead, you'd say "我 累 (wǒ lèi)".
• Negative form: The negative form of 是 is 不是 (bù shì), meaning "is not" or "to not be."
• Location: 是 is not used to indicate location. Use 在 (zài) for indicating location. See more about the differences between 是 and 在.