write + must do
kaka nakute wa ikenai
must do; have to do
meaning: have to write
もう遅いから寝なくちゃ。
mou osoi kara nenakucha.
It's late — I've gotta get to bed. casual
来週までにビザを更新しなくてはいけない。
raishuu made ni biza o koushinshi nakute wa ikenai.
I have to renew my visa by next week. neutral