Although I have seen some examples of negative expression, I have not been given any explanation in terms of grammar. It’s not as easy as, for example, in the English language, where any expression can be turned into a negative one. But then again, it’s also not something extremely difficult.
Keep in mind that what you need to do is putting the verb in negative. This changes the normal shape of the verb and can be formed in various ways.
With -eru/-iru verbs, the ending is replaced by -nai.
oki-ru oki-nai (to lift)
tabe-ru tabe-nai (to eat)
The negative formation of -u verbs is done by changing the vowel –u to –a, and by adding –nai at the end.
tor-u tor-anai (to take, to steal)
hanas-u hanas-anai (to talk)
If the verb ends in –tsu, then it is replaced by –ta and subsequently –nai is added at the end.
ma-tsu ma-tanai (to wait)
Finally, verbs ending in –u. Here, the vowel is replaced with –wa, as we can see in the verb au
a-u a-wa-nai (to know, to find)
Considering the above, we can use the verbs in various forms and finally form some negative expressions, as we have not studied them until now.