Negative verbs

話せます hanasemasu - can speak becomes...

私は、日本語が話せません。
watashi wa nihongo ga hanasemasen.
(I) can`t speak Japanese.

分かります wakarimasu - understand becomes...

私は、英語が分かりません。
watashi wa eigoga wakarimasen.
(I) don`t understand English.

If you can make the -masu form, just drop the す and add the せん。

You may have noticed there are no `no` words needed to make a negative like in English. You simply modify the verb`s ending.

To make the negative in the plain, or simple, form by taking the basic stem and adding ない to it.

With the `ru` verbs you simply drop the る and add ない as in 忘れる wasureru (to forget)...

日本語を忘れない。
nihongo o wasurenai.
(I) don`t forget Japanese.

And for the `u` verbs we change the ending `u` sound to a `a` sound as in 書く kaku -> 書か...

手紙を書かない。
tegami o kakanai.
(I) don`t write letters.

Finally we come to する and the other irregular verbs.

する is しない in the simple form and しません in the polite form

スカイダイビングをしません。
sukaidaibingu o shimasen.
(I) don`t do sky diving.

And 来る kuru is 来ない konai and 来ません kimasen in the formal...

ゴジラが来ない。
gojira ga konai.
Godzilla doesn`t come.

To review the 3 types of verbs click here.