ない Form:
The part of the words underlined below is called the ない Form.
The vowel before -masu in the verbs of this group is always [i] and is replaced by [-a] to make it a ない Form.
Exceptions to this rule are かいます、Where the i is replaced by wa and such verbs as はなします＆まちます、Where shi and chi is replaced by sa & ta respectively.)
Use of ない で ください Please do not:
しゃしん を とらない で ください。
Please do not take pictures.