If a sentence with an action verb, a 了 le (= suffix) and therefore with the aspect of completion, is negated, 没 méi (= not) or 没有 méi yǒu (= not have) are used and the 了 le is omitted.
Structure: Negation + verb – particle-le
我 | 没 | ( | 有 | ) | 买 | 书 | 。 |
wǒ | méi | _ | yǒu | _ | mǎi | shū | _ |
I | not have | _ | have | _ | buy | book | _ |
I, me, my | not have | ( | have, there is | ) | buy | book | 。 |
I haven't bought a book. |