Sentence Expansions

Japanese sentence expansions add meaning to a sentence without changing the verb's conjugation. Unlike derivative forms, they use extra grammar structures to express ability, experience, prohibition, obligation, and more.

Meaning	Verb	Adjective	Noun
1. Ability (Can do)	✅ (koto ga dekiru)	❌	✅ (ga dekiru)
2. Past experience	✅ (-ta koto ga aru)	❌	❌
3. Became able	✅ (yō ni naru)	✅ (-ku naru / ni naru)	✅ (ni naru)
4. Giving advice	✅ (ta hō ga ii)	✅ (hō ga ii)	❌
5. Permission	✅ (-te mo ii)	✅ (-te mo ii)	✅ (-te mo ii)
6. Prohibition	✅ (-te wa ikenai)	❌	❌
7. Try something new	✅ (-te miru)	❌	❌
8. Simultaneous Actions	✅ (nagara)	❌	❌

1. ことができる (koto ga dekiru) - Expressing Ability

Used to say "can do" something.

How to Form:

With Verbs: Dictionary form + ことができる
With Nouns: Noun + ができる

Type	Example	Expansion	Romaji	English
Verb	たべる (to eat)	たべることができる	taberu koto ga dekiru	Can eat
Noun	ピアノ (piano)	ピアノができる	piano ga dekiru	Can play the piano

💡 Note:

Use dekimasu for a more formal / polite use.

2. たことがある (-ta koto ga aru) - Expressing Past Experience

Used to express having done something before.

How to Form:

Verb (た-form) + ことがある

Verb	た-form	Expansion	Romaji	English
いく (to go)	いった	いったことがある	itta koto ga aru	Have gone

3. ようになる (yō ni naru) - Expressing Change in Ability or Habit

Used to express "becoming able to" or a habit change.

How to Form:

With Verbs: Dictionary form / Negative form + ようになる
With Adjectives: い-adjective → くなる / な-adjective → になる
With Nouns: Noun + になる

Type	Example	Expansion	Romaji	English
Verb	はなす (to speak)	はなせるようになる	hanaseru yō ni naru	Become able to speak
い-Adj	さむい (cold)	さむくなる	samuku naru	Become cold
な-Adj	きれい (beautiful)	きれいになる	kirei ni naru	Become beautiful
Noun	先生 (teacher)	先生になる	sensei ni naru	Become a teacher

4. ほうがいい (hō ga ii) - Giving Advice

Used to give advice ("You should" / "It's better to"). it can also be used for self-reflection, including regrets, realizations, or personal decisions.

How to Form:

For positive advice: Past tense (た-form) + ほうがいい
For negative advice: ない-form + ほうがいい
Can also be used with adjectives!

Type	Example	Expansion	Romaji	English
Verb	たべる (to eat)	たべたほうがいい	tabeta hō ga ii	You should eat
Verb	たべる (to eat)	たべたないほうがいい	tabenai hō ga ii	You shouldn't eat
い-Adj	あたたかい (warm)	あたたかいほうがいい	atatakai hō ga ii	It’s better if it’s warm

💡 Note:

ほうがいい can be used with な-adjectives to compare two states and suggest "It's better if..." or "You should choose..." one over the other.
The adjective いい can be conjugated to adjust the meaning (see later)

5. てもいい (-te mo ii) - Asking for/Giving Permission

Used to say "Is it okay if I..." or "You may do...".

How to Form:

Verb (て-form) + もいい
Adjective/Noun (て-form) + もいい

Type	Example	Expansion	Romaji	English
Verb	たべる (to eat)	たべてもいい	tabete mo ii	"May eat."
い-Adjective	あたたかい (warm)	あたたかくてもいい	atatakakute mo ii	"It's okay if it's warm."
な-Adjective	しずか (quiet)	しずかでもいい	shizuka de mo ii	"It's okay if it's quiet."
Noun	へや (room)	へやでもいい	heya de mo ii	"A room is fine."

6. てはいけない - Expressing Prohibition

Used to say "You must not..." or "It's forbidden to...".

How to Form:

Verb (て-form) + はいけない

Verb	て-form	Expansion	Romaji	English
たべる (to eat)	たべて	たべてはいけない	tabete wa ikenai	Must not eat

7. てみる - Trying Something New

Used to express trying something for the first time.

How to Form:

Verb (て-form) + みる

Verb	て-form	Expansion	Romaji	English
たべる (to eat)	たべて	たべてみる	tabete miru	Try eating

~~このゲームをやってみる。~~
Kono gēmu o yatte miru. → "I'll try playing this game."

8. ながら - Expressing Simultaneous Actions

Used to describe two actions happening at the same time.

How to Form:

Verb (ます-stem) + ながら

Verb	ます-stem	Expansion	Romaji	English
きく (to listen)	きき	ききながら	kiki nagara	While listening

Example

~~音楽を聞きながら勉強する。~~
Ongaku o kiki nagara benkyō suru. → "I study while listening to music."