Japanese Grammar 20 – Permissions, Prohibitions & Probability · N5

📋 Formation Reference — Permissions, Prohibitions & Probability

How to form and use these key N5 patterns. Press ▶ to hear examples.

PERMISSION — ～てもいいです

Pattern	Meaning	Formation	▶
～てもいいです ~te mo ii desu	May / It's OK to	て-form + もいいです
～てもいいですか ~te mo ii desu ka	May I ~?	て-form + もいいですか

PROHIBITION — ～てはいけません / ～ちゃだめ

Pattern	Meaning	Formation	▶
～てはいけません ~te wa ikemasen	Must not (polite)	て-form + はいけません
～ちゃだめ ~cha dame	Must not (casual)	て→ちゃ / で→じゃ + だめ

PROBABILITY & OPINION — でしょう / とおもいます / だけ

Pattern	Meaning	Formation
～でしょう ~deshou	Probably (polite)	plain form + でしょう
～だろう ~darou	Probably (casual)	plain form + だろう
～とおもいます ~to omoimasu	I think that ~	plain form + とおもいます
～だけ ~dake	Only	noun/verb + だけ

🗣 Example Sentences

See these patterns in context. Press ▶ to hear each sentence.

PERMISSION

Question

ここでしゃしんをとってもいいですか。

Koko de shashin wo totte mo ii desu ka.

May I take photos here?

しゃしんをとってもいいですか

shashin wo totte mo ii desu ka

→ "May I take photos?" (て-form + もいいですか)

Answer

はい、とってもいいですよ。

Hai, totte mo ii desu yo.

Yes, you may.

PROHIBITION

Polite

ここでタバコをすってはいけません。

Koko de tabako wo sutte wa ikemasen.

You must not smoke here.

タバコをすってはいけません

tabako wo sutte wa ikemasen

→ "Must not smoke" (て-form + はいけません)

Casual

はしっちゃだめ！

Hashiccha dame!

Don't run! (casual)

PROBABILITY & OPINION

Polite

あしたはあめでしょう。

Ashita wa ame deshou.

It will probably rain tomorrow.

Casual

あしたははれだろう。

Ashita wa hare darou.

It'll probably be sunny tomorrow.

Opinion

にほんごはむずかしいとおもいます。

Nihongo wa muzukashii to omoimasu.

I think Japanese is difficult.

むずかしいとおもいます

muzukashii to omoimasu

→ "I think [it is] difficult" (plain form + とおもいます)

Opinion

かれはくるとおもいます。

Kare wa kuru to omoimasu.

I think he will come.

ONLY — だけ

Example

みずだけのみます。

Mizu dake nomimasu.

I only drink water.

Example

これだけでいいです。

Kore dake de ii desu.

Just this is fine.

📋 Quick-Reference Cheatsheet ▼

Permission vs Prohibition — both use て-form

✅ PERMISSION

たべてもいいです

tabete mo ii desu

You may eat.

て-form + もいいです

🚫 PROHIBITION

たべてはいけません

tabete wa ikemasen

You must not eat.

て-form + はいけません

Casual prohibition — て→ちゃ / で→じゃ + だめ

✅ CORRECT

はしっちゃだめ

hashiccha dame

Don't run!

はしって → っちゃ contraction

❌ COMMON MISTAKE

はしってはだめ

hashitte wa dame

Intended: Don't run!

Grammatically OK but unnatural in casual speech — use ～ちゃだめ instead.

でしょう (polite) vs だろう (casual) — both mean "probably"

✅ POLITE

あめでしょう

ame deshou

It will probably rain.

Use in formal / public contexts

✅ CASUAL

あめだろう

ame darou

Probably rain.

Use with friends or in inner monologue

とおもいます requires PLAIN form

✅ CORRECT

くるとおもいます

kuru to omoimasu

I think he will come.

Plain form (くる) before と

❌ COMMON MISTAKE

きますとおもいます

kimasu to omoimasu

Intended: I think he will come.

Never use ます-form before と — always use plain form.

だけ vs しか〜ない — both mean "only"

✅ だけ (positive verb)

みずだけのみます

mizu dake nomimasu

I only drink water.

だけ uses a positive verb

✅ しか (negative verb)

みずしかのみません

mizu shika nomimasen

I only drink water.

しか always pairs with a negative verb

A — Flashcards

Click a card to flip it. Use ▶ to hear the Japanese.

tap to flip

1 / 10

B — Listen & Choose the Meaning

Press ▶ to hear each phrase, then choose the correct English meaning.

D — Listen & Write in Romaji

Press ▶ to hear each phrase, then type what you heard in romaji.

💡 Tip: Long vowels → double the vowel (おう = ou / oo). Double consonants → write them twice (きって = kitte).

📖 Grammar Deep Dive ▼

てもいい — Permission from "even if"

てもいい literally means "even if you do ~, it is good." The て-form sets up a conditional "even if" (ても), and いい means "good / fine." Together they grant permission naturally. • Polite: てもいいです • Question: てもいいですか • Casual: てもいい (drop です)

[て-form] もいいです

[te-form] mo ii desu

→ "It is OK to ~" / "You may ~"

ここにすわってもいいですか。

Koko ni suwatte mo ii desu ka.

May I sit here?

てはいけない — Prohibition from "won't do"

てはいけない literally means "if you do ~, it won't do." The は here is a topic/contrast particle that adds emphasis. いけない (from いけません) means "won't do / is no good." • Polite: てはいけません • Semi-casual: てはいけない • Very casual: ちゃだめ / じゃだめ

[て-form] はいけません

[te-form] wa ikemasen

→ "You must not ~"

ここでタバコをすってはいけません。

Koko de tabako wo sutte wa ikemasen.

You must not smoke here.

でしょう — Polite guessing for weather, situations, and softening

でしょう attaches to the plain form to express probability or a soft guess. It is also used to invite agreement ("right?") when spoken with rising intonation. • Weather forecasts always use でしょう • Rising tone (でしょう↗) = "isn't it?" / "right?" • Casual equivalent: だろう

[plain form] でしょう

[plain form] deshou

→ "It is probably ~" / "~ right?"

あしたはあめでしょう。

Ashita wa ame deshou.

It will probably rain tomorrow.

とおもいます — Expressing your opinion (plain form required)

と is a quotation particle. おもいます means "to think." Together とおもいます reports a thought. • Always use PLAIN form before と — never ます-form • とおもいます = what you think right now • とおもっています = an ongoing or long-held belief (or what you think someone else believes)

[plain form] とおもいます

[plain form] to omoimasu

→ "I think that ~"

にほんごはむずかしいとおもいます。

Nihongo wa muzukashii to omoimasu.

I think Japanese is difficult.

だけ — Only / Just (attaches directly)

だけ attaches directly after a noun, verb, or quantity with no space. • みるだけ (just looking) • すこしだけ (just a little) • これだけ (just this) • Contrast with しか〜ない: both mean "only" but しか requires a negative verb. だけ uses a positive verb.

[noun / verb] だけ

[noun / verb] dake

→ "Only ~" / "Just ~"

みずだけのみます。

Mizu dake nomimasu.

I only drink water.

📝 Key Vocabulary ▼

Japanese	Romaji	English
しゃしん	shashin	photo / photograph
タバコ	tabako	cigarette / tobacco
すう	suu	to smoke / to inhale
はしる	hashiru	to run
はれ	hare	sunny / clear weather
あめ	ame	rain
むずかしい	muzukashii	difficult
くる	kuru	to come
だめ	dame	no good / not allowed
いい	ii	good / fine / OK