To say that you have to or must do something, you can use a verb in plain negative form + ~と いけない.
| I’m so tired. I have to sleep soon. | もう、 とても 疲れて いる。 すぐ 寝ない と いけない。mou, totemo tukarete iru. sugu nenai to ikenai. |
| That teacher’s class is hard. The homework has to be written in Japanese. | あの 先生 の 授業 は 難しい です。 宿題 は 日本語 で 書かない と いけない。ano sensei no zyugyou ha muzukasii desu. syukudai ha nihongo de kakanai to ikenai. |
You can also use いけません in place of いけない to make the sentence more formal.
| We have to clean before the guests come. | お客さん が 来る 前 に、 掃除しない と いけません。okyakusan ga kuru mae ni, souzisinai to ikemasen. |
It's also possible to replace といけない with とダメです. ダメ essentially means no good, but it can also mean cannot/not allowed. Note that ダメ is spelled using katakana here, but in other cases it's often spelled using hiragana.
| Children have to go to school every day. | 子供 は 毎日 学校 に 行かない と ダメ です。kodomo ha mainiti gakkou ni ikanai to dame desu. |
In very informal situations you can simply use the verb in plain negative form + ~と, omitting the final いけない.
| Watch out. It’s super hot. You have to drink some water. | 気 を 付けて ね。 めちゃ 熱い だ。 お水 を 飲まない と。ki wo tukete ne. metya atui da. omizu wo nomanai to. |
There are also different ways to say must do, but we will look at those in a later lesson.
