Defference between -ません(masen) and -ない(nai)
When you learn -nai form, you will think how it is different from -masen.
-ません(masen) is the negative form of -ます(masu) . They are used in relatively formal situations.
・Watashi wa ocha wo nomimasu.(affirmative)
・Watashi wa ocha wo nomimasen. (negative)
On the other hand, -ない(nai) is the negative form of the plain/dictionary form of verbs.
These two are used in casual conversations among family members or friends. (They are also used in very formal writings such as theses or novels, though.)
・Asagohan, taberu? (affirmative question)
・Asagohan, tabenai.(negative)
