Very often you want to express something that you heard. You simply attach そうだ to the end of the plain form of the sentence that you heard. For example, if you want to say “I heard that the weather would become nice tomorrow.” – You would need to express “The weather would become nice tomorrow” in plain form, and then attach そうだ (casual) or そうです (polite) to it.

To construct the plain present tense form of a phrase, check if it ends with a noun, an adjective or a verb, and do the following:

1. Noun/な-adjective: (drop な) and attach だ to it
2. い-adjective: leave it unchanged
3. Verb: change it to its dictionary form (ends with う or る)

明日はいい天気になるそうです。

I hear that the weather will be nice tomorrow.

明日はいい天気になる + そうだ

そとは暑いそうです。

I hear that it is hot outside.

そと = outside, 暑い = hot

彼は、学生だそうです。

I hear that he is a student.

学生 = student

だそうです。

That’s what I heard.

だ indicates the state of being.

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You would change the sentence to plain past tense form if the sentence is in past tense. If you are not sure what it means, please look up a detailed description for plain forms of noun phrases, adjectives and verbs.

In English we have tense agreement. For example, it is technically incorrect if you say “I heard that he is a student.” In Japanese, however, そうだ already implies it is something that you heard, and you do not need to change the tense of the original sentence.

毎日学校に行ったそうです。

I heard that he went to school everyday.

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Recall that an adverb is usually used to modify a verb, just as an adjective is usually used to modify a noun. In English, in general, you add “ly” to change adjectives to adverbs. For example, aggressive is an adjective and aggressively is an adverb. In Japanese, there is also a regular way to change adjectives to adverbs, as follows:

い-adjective: change い to く

な-adjective: change な to に

Exception: change いい (good) to よく (well).

Examples

早い （はやい）is an い-adjective which means early. When it is used as an adverb, change い to く and it becomes 早く.

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Unlike English, which you may put adverb either before or after the main verb in a sentence, you usually put the Japanese adverb before the main verb.

静か （しずか）is a な-adjective which means quiet. When it is an adverb, it becomes 静かに.

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In order to make more complex sentences, you need to use verbs or adjectives other than their simplest dictionary form. In English, in general, you add “ly” to change adjectives to adverbs. However, for example, when you change “happy” to “happily,” you need to modify “happy” to “happi” before adding “ly” at the end of the word. Technically this kind of modification is called morphological changes.

In Japanese, a widely used morphological changes is the て-form (te-form). By making a verb or an adjective in its て-form, you are ready to “glue” the word with more unit of meanings.

て-form of Japanese Verbs

If you know how to conjugate Japanese verbs to their plain past form (た-form), you shouldn’t have any problems to conjugate verbs to their て-form, as the conjugation rules are identical.

る-verbs Ending with	Replace with	Example
る	→ て	食べる → 食べて

う-verbs Ending with	Replace with	Example
す	→ して	出す→ 出して
く	→ いて	書く→ 書いて
ぐ	→ いで	泳ぐ→ 泳いで
る, う or つ	→ って	作る→ 作って
む, ぶ or ぬ	→ んで	飲む→ 飲んで

Irregular verbs	Replace with	Example
する	→ して	勉強する → 勉強して
くる	→ きて	持ってくる → 持ってきて

Verb+ている and Ongoing Actions

One of the easiest applications of て-form is to represent ongoing actions. You attach いる to the verb in て-form. It is equivalent to gerund (-ing) form in English.

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Verb+ている and Resultant State

However, when the verb in use are in motions, such as 行く, 来る, 帰る or 出かける, its ている form does not imply an ongoing action. Instead, it represents a resultant state, meaning that the action is already completed. You may simply consider the て-form as a connector between the motion verb and the verb いる.

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In many other cases, the context or the nature of the verb implies that its ている form represents a resultant state.

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Verb+ている and Habitual Actions

You may also use ている form to express repeated habitual actions.

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It is never too much to emphasize that being polite is very important in Japanese culture, and before you really understand the difference and implication of casual speech, you will almost always want to use polite speech in your conversation. This is the disclaimer before I talk about casual speech in Japanese.

There are 2 basic rules. First, use plain forms (or so-called dictionary forms) for verbs and adjectives. Second, particles such as は(wa), を(o), に(ni), が(ga) are omitted when there is no confusion caused.

The following examples show the contrast between polite speech and casual speech. Note that ですか(desu ka) is omitted in the first question and a rising tone is used instead.

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学生 is a noun, but the same idea applies to verbs and adjectives. You just need to use the plain form in each case for casual speech.

The use of particle よ(yo) at the end of the 2nd and 3rd examples is to make the sentences smoother and express a certain kind of emotion. Particle ね(ne) is also often used.

Particle は(wa) is dropped in the examples. Do not drop the particle (or any other particles) when it carries additional functions other than a “marker.” For instance, when は is used to contrast or compare two things, do not drop the particle in casual speech. A similar example is to drop を(o) when it is a purely object marker.

You may notice that “Yes” and “No” in the examples above have different forms for casual speech. In fact, there are a few special forms for casual speech, as listed in the following table:

Polite Speech	Casual Speech	English Definition
はい	うん	yes
いいえ	ううん	no
…て下さい	…て	please …
…ている	…てる	(continuous form)
…んですか	…の？	(question ending)
…んです	…んだ (man)	(end of a statement)
	…の (woman)

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Conjugation is to modify of a verb or an adjective in order to fulfil a change in tense or to supplement additional meanings.

All Korean conjugation for verbs and adjectives are under one of the following 3 categories:

1. 고-type: Original Stem + Suffix
2. 으-type: Alternate Stem + (으) + Suffix
3. 어-type: Alternate Stem + 어/아 + Suffix, Vowel Contractions

The basic idea is to identify the word stem and attach a suffix to the stem.

1. 고-type Conjugation

This is named after the basic 하고 conjugation. Original stem is always used, with the following exceptions:

• For ㄹ-irregular, when the attaching suffix starts with ㄴ, ㅅ or ㅂ (e.g. 는, 네, 습니다), alternate stem is used (i.e. ㄹ is dropped).
• For ㅎ-irregular, use alternate stem when the attaching suffix is 네.

Examples

Plain Form	Meaning	Stem 1	Stem 2	+고	+습/ㅂ니다	+네	Remarks
하다	do	하	하	하고	하습니다	하네
먹다	eat	먹	먹	먹고	먹습니다	먹네
알다	know	알	아	알고	압니다	아네	ㄹ-irregular
그렇다	to be so	그렇	그러	그렇고	그렇습니다	그러네	ㅎ-irregular

Note: Original Stem = Stem 1, Alternate Stem = Stem 2.

2. 으-type Conjugation

Use alternate stem and if the stem ends with a consonant, insert 으 after the stem.

However, there are 3 exceptions:

• For ㅅ-irregular, 으 is always inserted.
• For ㄹ-irregular, if the suffix starts with 면 or 러, use original stem and do not insert 으.
• For 르-irregular, use original stem instead.

Examples

Plain Form	Meaning	Stem 1	Stem 2	+ (으)세요	+ (으)면	+ (으)러	Remarks
하다	do	하	하	하세요	하면	하러
먹다	eat	먹	먹	먹으세요	먹으면	먹으러
알다	know	알	아	아세요	알면	알러	ㄹ-irregular
짓다	build	짓	지	지으세요	지으면	지으러	ㅅ-irregular
고르다	choose	고르		고르세요	고르면	고르러	르-irregular

3. 어-type Conjugation

You can consider 어-type conjugation as a 2-step process. First you need to determine whether 아 or 어 should be attached, then you need to do a vowel contraction if necessary.

Use alternate stem as word stem for all 어-type conjugation, except that for ㄹ-irregular, use original stem instead.*

The following rules determine whether to attach 어 or 아 before the suffix:

1. If the last vowel of the stem is a 오 or 아, attach 아 + suffix.
2. If the last vowel is 으 and its previous hangul has a 오/아 vowel, attach 아 + suffix.
3. Otherwise, attach 어 + suffix.

Next, if the stem has no ending consonant, contract the last vowel of the stem and the added 아/어 as shown in the table below. Pay special attention to 하다-related verbs and adjectives, and ㅅ-irregular, as they are the exceptions.*

Case	Contraction	Example	Meaning	Stem + 아/어요	Remarks
*	하 +아 → 해	공부하다	study	공부하 + 아요 → 공부해요	하다-related
1	아 +아 → 아	가다	go	가 +아요 → 가요
	오 +아 → 와	오다	come	오 +아요 → 와요
		돕다	help	도오 +아요 → 도와요	ㅂ-irregular
2	으 +아 → 아	바쁘다	busy	바쁘 +아요 → 바빠요	으-irregular
		고르다	choose	골르 +아요 → 골라요	르-irregular
3	우 +어 → 워	배우다	learn	배우 +어요 → 배워요
		춥다	cold	추우 +어요 → 추워요	ㅂ-irregular
	으 +어 → 어	쓰다	write	쓰 +어요 → 써요	으-irregular
		부르다	call	불르 +어요 → 불러요	르-irregular
	이 +어 → 여	치다	hit	치 +어요 → 쳐요
	어 +어 → 어 or 애	건너다	go over	건너 +어요 → 건너요
		그렇다	to be so	그러 +어요 → 그래요	ㅎ-irregular
	외 +어 → 왜	되다	become	되 +어요 → 돼요
	애 +어 → 애	지내다	spend time	지내 +어요 → 지내요
	여 +어 → 여	펴다	unfold	펴 +어요 → 펴요
All	No Contraction	먹다	eat	먹 +어요 → 먹어요
		듣다	listen	들 +어요 → 들어요	ㄷ-irregular
		놀다	play	놀 +아요 → 놀아요	ㄹ-irregular*
		낫다	get better	나 +아요 → 나아요	ㅅ-irregular*

Use original stem for ㄹ-irregular, and never do vowel contractions forㅅ-irregular.