So far, with the te form, we have learned that here are two main patterns for inflecting verbs: a simple one, where you remove the ます and replace it with て, and a complicated one, where you also have to change the letter that comes before ます.
Now let’s look at the –nai form
(1) Simple pattern
When we make the –nai form of a verb that uses the simple pattern to make its –te form, it’s again quite simple: Just replace the final ます orて with ない. No matter what the letter before ます is, it’s always the same
- Remove ます たべ
ます→ たべ - Add ない たべ ＋ ない → たべない
Here’s a list of some common verbs that follow the simple pattern:
| ます form | English | てform | ないform |
| たべます | Eat | たべて | たべない |
| あけます | Open | あけて | あけない |
| おります | Get down/off | おりて | おりない |
| おちます | Fall | おちて | おちない |
| あびます | Wash | あびて | あびない |
| します | Do | して | しない |
(2) Complicated pattern
When we make the –nai form of a verb that follows the complicated pattern, again, you remove the final ます, but additionally, before adding ない, you have to change the letter that came before ます . For example, with おわります: you remove the finalます, but you also have to replace the り with ら before you add the て.
- Remove ます おわり
ます→ おわり - Change last letter おわ
り＋ ら → おわら - Add て おわら ＋ て → おわらない
Here, you change the letter that came before ます to an -a sound. For –nai forms, the second step is always the same, regardless of the letter preceding ます, so きります, which also has りbefore the ます, follows the same system as おわります。
きります → きらない
And かきますand おきます, which have きbefore the ますalso behave in a similar way.
かきます → かかない
おきます → おかない
Here is a table of the different ways to make –nai forms for verbs that follow the complicated pattern.
| Letter before ます | ます form | English | てform | ないform |
| き | かきます | Write | かいて | かかない |
| ぎ | およぎます | Swim | およいで | およがない |
| し | はなします | Speak | はなして | はなさない |
| ち | まちます | Wait | まって | またない |
| に | しにます | Die | しんで | しなない |
| び | あそびます | Play | あそんで | あそばない |
| み | よみます | Read | よんで | よまない |
| り | きります | Cut | きって | きらない |
We learned that there is an exception for complicated pattern verbs with し before ます, in that the with the –te form, the しdoes not change. Now you can see that with the ないform, the しdoes change, and the verbs follow the same pattern as the others.
In romaji, it’s even simpler, just remove –imasu, and add –anai.
(3) Irregular verbs
いきます, which we have learned is an irregular verb uses the complicated system to make its –nai form
| Letter before ます | ます form | English | ないform |
| き | できます | Be able | できない |
| き | かきます | Write | かかない |
| き | いきます | Go | いかない |
きます, which uses the simple system for its –te form, has an irregular –nai form in which the verb stem changes from ki– to ko–
| Letter before ます | ます form | English | ないform |
| き | かきます | Write | かかない |
| き | できます | Be able | できない |
| き | きます | Come | こない |
Conclusion
Now that we’re learning the –nai form, we can see the two types of inflection becoming clearer.
We can see that 1) verbs using the simple pattern to make their –te forms also use the simple pattern to make their –nai forms, and 2) those that use a variant of the more complicated –te form pattern likewise us a pattern system for their –nai forms. The pattern system for –nai forms is less complicated than that for -te forms in that it is uniform for all verbs in this class, regardless of the letter that comes before ます.