We learned how to say we don’t have to do something in the last section but we did not cover how to talk about things that have to be done. Because of the way it’s phrased in Japanese, the grammar for saying something has to be done is completely different than the grammar for saying something doesn’t have to be done.
First, let’s look at how to express something that one must not do.
Things that one must not do
Things that one must not do are expressed by using one of the three words: 「いけない」、「ならない」、 and 「だめ」. These are all negative expressions (the first two is actually using the negative form) meaning that something won’t do or is no good. Conjugating these expressions are simple if we know where they originate from.
- いける (ru-verb) – can work; can make it; lit: can go （potential form of 「行く」）
- なる (u-verb) – to become
- 駄目 【だ・め】 (na-adj) – no good
While we can use 「いけない」 and 「だめ」 by themselves as shown in the examples below 「ならない」 cannot be used by itself.
Example
- ここで携帯を使うのはだめ？
Is using cell phone here bad? - それはいけませんね。
That’s wrong/bad/no good. - ご両親に教えたのがいけなかったんだよ。
Telling (your) parents is what was no good.
We can use either of the three words with verbs to say that action is no good or in essence, “one must not do the action” by using the following rule.
- Take the te-form of the verb, add the 「は」 (wa) particle and then attach either 「いけない」、「ならない」、 or 「だめ」.
Example- 食べて＋は＋いけない／ならない／だめ
= 食べてはいけない、食べてはならない、食べてはだめ - 買って＋は＋いけない／ならない／だめ
= 買ってはいけない、買ってはならない、買ってはだめ - して＋は＋いけない／ならない／だめ
= してはいけない、してはならない、してはだめ
- 食べて＋は＋いけない／ならない／だめ
Example
- 男の人はここに入ってはいけませんよ。
Men must not enter here, you know. - お酒を飲んだ人は、車を運転してはならない。
People who drank alcohol must not drive cars. - 悪い言葉を生徒に教えてはだめですよ。
(You) must not teach students bad words, you know.
Things that must be done
In order to say that something must be done, we say not doing something is bad by using the previous grammar we just learned but with negative verbs. You can also use two of the conditionals we learned in the last chapter. This grammar may be a bit confusing at first because we need to use double negatives to say one must do something.
- Negative te-form +「は」 (wa) particle + いけない／ならない／だめ
- Negative verb + 「と」(conditional) + いけない／ならない／だめ
- Negative verb + 「ば」 conditional + いけない／ならない／だめ
Comic 13
- 先生 【せん・せい】 – teacher
- トイレ – toilet; bathroom
- 行く 【い・く】 – to go
- いい (i-adj) – good
- また – again
- 駄目 【だ・め】 (na-adj) – no good
- 無駄 【む・だ】 (na-adj) – futile
- 短い 【みじか・い】 (i-adj) – short
- 間 【あいだ】 – interval (between)
- 宿題 【しゅく・だい】 (n) – homework
- 出来る 【で・き・る】 (ru-verb) – to be able to do
ジョン：先生、トイレに行ってもいいですか。
John: Teacher, can (I) go to the bathroom?
先生：また行かないとダメなのか？
Teacher: (You) have to go again?
アリス：無駄よ。トイレに行っている短い間に宿題なんか出来ないよ。
Alice: (It’s) useless, you know. (You) can’t do something like homework in (the) short interval of going to the bathroom.
Example
- この薬は一日に三回飲まなくてはなりません。
(You) have to take this medicine 3 times a day. - 明日までに宿題をしないといけない。
(I) have to do homework by tomorrow. - まだ早いのにもう帰らなければいけないんですか。
Even though (it’s) still early, do (you) have to go home?
Casual variatons
There are a couple of casual variations of the grammar we just learned listed below.
- Replace 「ては」 with 「ちゃ」
- Replace 「ければ」 with 「きゃ」
Example
- 男の人はここに入っちゃだめよ。
Men must not enter here, you know. - まだ早いのにもう帰らなきゃいけないの？
Even though (it’s) still early, do (you) have to go home?
Things can get quite lengthy with the double negative required to describe an action that must be done. When using the casual variations with the negative, you can also omit the 「いけない／ならない／だめ」 part of the grammar. This also applies to the 「と」 conditional.
Example
- もっと勉強しなくちゃ。
(I) have to study more. - 明日までに宿題をしないと。
(I) have to do homework by tomorrow. - もう帰らなきゃ.
(I) have to go home already.