不 bù is used with the following verbs for past, present and future: adjective-verbs, stative verbs, modal verbs.
Adjective Verb
我 | 不 | 大 | 。 |
wǒ | bú | dà | _ |
I | not | big | _ |
I, me, my | no, not, after negative question: yes | big, old, main | 。 |
I am not big. |
Stative Verb
我 | 不 | 是 | 老 | 师 | 。 |
wǒ | bú | shì | lǎo | shī | _ |
I | not | be | old | teacher | _ |
I, me, my | no, not, after negative question: yes | to be, correct, yes | teacher | 。 | |
I am not a teacher. |
Modal Verb
我 | 不 | 回 | 去 | 。 |
wǒ | bù | huí | qù | _ |
I | not | return | go | _ |
I, me, my | no, not, after negative question: yes | go back | 。 | |
I don't go back. |
If one negates an action-verb, 不 bù can only be used for present and future tense. For the past tense one must use 没 méi (= not).
Action Verb
我 | 不 | 去 | 。 |
wǒ | bú | qù | _ |
I | not | go | _ |
I, me, my | no, not, after negative question: yes | go to, pass away, remove | 。 |
I dont go. |