write + not + must do
kakanai to ikenai
must do; have to do
meaning: have to write
明日までにレポートを出さないといけない。
ashita made ni repooto o dasanai to ikenai.
I have to hand in the report by tomorrow. neutral
もう帰らないと。
mou kaeranai to.
I've gotta head home. casual