Auxiliary verb

Also known as: modal verb, 助动词 (zhùdòngcí), 情态动词 (qíngtài dòngcí) and 能愿动词 (néngyuàn dòngcí).

Auxiliary verbs are "helping" verbs that come before main verbs and help express a tone or mood. (The word "modal" comes from "mood.") In English, auxiliary verbs include words like "should," "will," and "can," which all change something about the situation and the speaker's attitude. Auxiliary verbs express capability, possibility, necessity, obligation or willingness.

Characteristics

In sentences with auxiliary verbs, the auxiliary verb is the one that gets modified. That is, if you want to negate a sentence with an auxiliary verb, put "不" before the auxiliary, not the main verb.

Also, unlike normal verbs, auxiliary verbs can't be reduplicated, nor can they take the aspect particles: 了 (le), 着 (zhe), and 过 (guo).

Finally, when you are responding to a question that uses an auxiliary verb, you reply with the auxiliary verb, not with the main verb that it modifies.

Grammar Patterns for Auxiliary Verbs

Sources and further reading