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-아/어/여서 Grammar: 'Because' in Korean with Free Worksheet

안녕하세요? This is My Korean Lesson for your Korean studying! 🤗 In this lesson, I'll show you how to talk about a reason. I actually prepared the two ways for you. One is the conjunction and the other is a connective ending. The second one is a big grammar and the main grammar of today. Please take your time and follow me one by one.


By the end of the lesson, you will be able to construct sentences such as "I didn't go to the mountain because it was raining." or "I couldn't go to school because I was sick." Are you ready to get started? Let's begin!

Because in Korean 아어여서 Grammar Lesson


1. Words

Here are the words you will need in this lesson! If you click the speaker button, you'll be able to listen to it. Please listen and repeat each word.


그래서 so


날씨 weather


소풍 picnic


시험 test


열심히 hard, diligently


아프다 to be sick


너무 too



2. 그래서 and 아/어/여서 grammar

A. 그래서

Before we start our main lesson today, let's start with a quick conjunction lesson. 그래서 is a conjunctive adverb meaning "so" in English. It connects two sentences adding the cause, basis, or condition. It is attached to the second sentence, which is the result of the first sentence.


  • 날씨가 좋아요. 그래서 소풍을 가요. The weather is nice. So, we are going to the picnic.

  • 봄은 따뜻해요. 그래서 봄이 좋아요. The spring is warm. So, I like spring.


B. 아/어/여서

아/어/여서 came from the connective ending 아서/어서/여서. Since it is too long, people shortened it. Anyway, it can combine two sentences into one. While that, it adds a "reason" or "cause" meaning like "because" in English. It can be attached to the first stem to show that the first part of the sentence is the reason for the second part.


  • 따뜻하다 to be warm + 봄이 좋다. like Spring.

→ 따뜻해요. 그래서 봄이 좋아요. Those are two sentences.

= 따뜻해서 봄이 좋아요. We can make it into one sentence with 아/어/여서.

I like spring because it is warm.


Thanks to 아/어/여서 two verbs are connected into one. 아/어/여서 attaches to the first part 따뜻하다 (to be warm) and turns it into 따뜻해서. It means "because it is warm". This part is the reason for the second part. 봄이 좋아요 "I like spring".


The example of 아어여서 grammar


3. Conjugation Rules

A. Regular Conjugation Rules

아/어/여서 can be attached to verb stems, adjective stems, N이다 (be), and N이/가 아니다 (be not). It is important to pay attention to the last vowel of the stem, as the conjugation rules are dependent on it. Fortunately, both verbs and adjectives follow the same rules. To make things easier, I will provide examples of both verbs and adjectives for each rule.


As the last vowel is the matter, it follows the same rule as the tense conjugation. When you change the verbs and adjectives into the informal (conversation) present tense, we attach 아요, 어요, 여요. Now, we will add 아서, 어서, and 여서 to the same category. In short, you can replace 요 with 서 to make a "because" form.


1. ㅏ, ㅗ + 아서

When the last syllable of the stem has ㅏ or ㅗ as a vowel, you must add 아서. It applies to both a verb and an adjective. As you saw in the present tense rule, the same combinations will happen for words that do not end with a final consonant.


  • 살다 to live → 살 → 살아서

  • 사다 to buy → 사 → 사아서 → There is nothing to prevent 사 and 아 sticking to each other! → 사서

  • 작다 to be small → 작 → The vowel is ㅏ so we need 아서. → 작아서



2. 하다 + 여서 → 해

When the last syllable of the stem is 하, in other words, when a verb or an adjective ends with 하다, you add 여서 to the stem. However, 하여서 is an old-fashioned way. People use "해서" these days.


  • 하다 → The stem of 하다 verbs and adjectives are 하. → 하+여서 → 해서

  • 공부하다 to study → 공부해서

  • 날씬하다 to be skinny → 날씬해서



3. Other than number 1 and number 2 + 어서

When the vowel is not ㅏ or ㅗ or 하, you can use this third rule! So, the most of words will use 어서. You can see this rule has the same pattern as the informal present tense, right?


  • 먹다 to eat → 먹 → The vowel is not ㅏ or ㅗ. We need to attach 어서. → 먹어서

  • 멀다 to be far → 멀 → 멀어서

  • 있다 to stay / to be existing → 있 → 있어서



B. Irregular Conjugation Rules

Let's check out the irregular rules (불규칙) as well! Again, they'll be all the same with the present tense rule. You can simply change 아요, 어요, 여요 into 아서, 어서, 여서!


1. 불규칙 ㄷ verbs: ㄷ → ㄹ + 아/어서

As there are no irregular adjectives that have the consonant ㄷ, let's examine some examples of irregular verbs that use this consonant. To conjugate these verbs, you need to change ㄷ to ㄹ and then add either 아서 or 어서 using the regular conjugation rules.


  • 깨닫다 to realize → 깨닫 → 깨달 → Since the last vowel is ㅏ, let's add 아. → 깨달아서

  • 듣다 to listen → 듣 → 들 → 들어서



2. 불규칙 ㅅ verbs, adjectives: Drop ㅅ + 아/어서

If a vowel or an adjective stem ends with ㅅ, we remove the final consonant ㅅ. Then, attach 아서 or 어서 using the regular rules based on the last vowel.


  • 낫다 to heal → 낫 → 나 → 나아서

  • 낫다 to be better → 낫 → Drop the ㅅ. → 나 → 나아서


Here's something interesting for you to remember. The Korean word 낫다 has both verb and adjective meanings. They are homonyms. When used as a verb, it means 'to heal,' but when used as an adjective, it means 'to be better.' The only way to determine which meaning is intended is by examining the context. Additionally, it's important to note that the adjective 낫다 is only an irregular ㅅ adjective.



3. 불규칙 ㅂ verbs, adjectives: Drop ㅂ + 와서/워서

For irregular ㅂ verbs, you will erase ㅂ first. Then add 와서 or 워서. For ㅏ or ㅗ words, we will add 와서 instead of 아서. Other than that, please add 워서, instead of 어서.


  • 줍다 to pick up → 줍 → Drop the final consonant ㅂ. → 주 → Since the vowel is ㅜ, it follows the rule 3. However, since it is a ㅂ word, you'll add 워서. → 주워서

  • 춥다 to be cold → 춥 → 추 → The vowel is ㅜ. We need 워서. → 추워서


Here, take a close look. 줍다 and 춥다 look so similar! You'd better watch out! The small line above ㅈ makes a big difference!



4. 불규칙 ㅎ adjectives: Drop ㅎ + ㅣ서

When a stem ends with ㅎ, verbs follow regular rules while adjectives are irregular. Just like you changed the irregular ㅎ adjectives into the present tense, we need to add the vowel ㅣ first and then 서.


  • 파랗다 to be blue → 파랗 → Erase ㅎ. → 파라 → add ㅣ서 → 파래서

  • 뿌옇다 to be foggy → 뿌옇 → 뿌여 → 뿌예 → 뿌예서



5. Others(불규칙 ㅡ and 르)

The irregular ㅡ and 르 are a bit advanced level. You'll need to drop the vowel ㅡ and add 아서 or 어서 depending on the remaining vowel. If you are a beginner, try to memorize them as one chunk for now. If you want to learn the details about this rule, please read my other post.


  • 부르다 to call / to sing → 불러서

  • 아프다 to be sick → 아파서

  • 예쁘다 to be pretty → 예뻐서

  • 크다 to be big → 커서



C. N이다/아니다 conjugation rules

We are not done yet! I told you it is a big grammar! If you are too tired, practice up to the above and come back to this part later.


If you want to say sentences using the reasoning parts like "because I am a student," or "because I am not a student," we need to use 이다 (to be) or 아니다 (not to be). 이다 and 아니다 are very basic and important words, so if you are not familiar with them, please check my other post first.


1. N이다

N이다 means "to be N". What is the stem of 이다? Yes, it is 이. What is the vowel of this word? It is the vowel "ㅣ". Since it is not "ㅏ" or "ㅗ," that means you have to use the regular rule number 3. So, you add 어서 to 이 and make 이어서.


  • 선생님이어서 because I am a teacher

  • 의사이어서 because I am a doctor


However, if the noun ends with a vowel like 의사, 간호사, or 가수, people usually use the "여서" form. When the noun ends with a final consonant, please add 이어서. When it ends with no final consonant add 여서.


  • 받침 O + 이어서: 학생이어서 because I am a stuent

  • 받침 X + 여서: 간호사여서 = because I am a nurser


In daily conversation, 이어서 is often used as 이라서. 여서 usually becomes 라서. That means you'll use 이어서 and 여서 more often in writing. However, those are just general rules, you can interchange them. Here is the summary chart for you.

받침O: N이다

-이어서/-이라서

받침X: N이다

-여서/-라서

학생이다

be a student

학생이어서/

학생이라서

의자이다

be a chair

의자여서/

의자라서

선생님이다

be a teacher

선생님이어서/

선생님이라서

가수이다

be a singer

가수여서/

가수라서


2. N이/가 아니다

N이/가 아니다 means "not to be N." Depending on the final consonant of the noun, attach either 이 or 가. 아니다 will be conjugated 아니어서. However, in daily conversations, the 아니라서 form is more often used.


  • 받침 O + 이 아니어서 or 이 아니라서:

책상이 아니여서 = 책상이 아니라서 = because it is not a desk,


  • 받침 X + 가 아니어서 or 가 아니라서

의자가 아니어서 = 의자가 아니라서 =because it is not a chair,



4. Sentence Information

A. Tense

When you connect two sentences with 아/어/여서, the tense will be revealed at the end of the sentence. Even though you are talking about past events, the first part of the sentence with 아/어/여서 won't have any past tense words (았/었/였). Let's compare the present sentence and the past sentence.


  • A. 비가 많이 와요. 그래서 산에 안 가요. It is raining a lot. So, I don't go to the mountain.

→ 비가 많이 와서 산에 안 가요. Because it is raining a lot, I don't go to the mountain.


  • B. 비가 많이 왔어요. 그래서 산에 안 갔어요. It rained a lot. So, I didn't go to the mountain.

→ 비가 많이 와서 산에 안 갔어요. Because it rained a lot, I didn't go to the mountain.


Compare A and B. A is the present tense sentence while B is the past tense sentence. How can you tell? Yes, you can do so by the end of a sentence. 가다 is conjugated to 가요 in the sentence A and 갔어요 in the sentence B!


But for both, the first part of the sentence is 와서. So, no matter what tense you are using, 아/어/여서 part doesn't imply a tense. Here is a quick conclusion for you. The tense of the entire sentence is determined by the tense of the last verb.



B. Sentence Types

The sentence types mean statement, question, command, and propositive. The types of sentences will be revealed at the end of the sentence. When you use 아/어/여서 grammar, there are only two types of sentences that can be used. Those are statements and questions. You can't command or suggest someone with 아/어/여서!


  • (O) 시험이 있어서 열심히 공부했어요. I studied hard because I had an exam.

  • (O) 시험이 있어서 열심히 공부했어요? Did you study hard because of the exam?

  • (X) 시험이 있어서 열심히 공부하세요. (Command)

  • (X) 시험이 있어서 같이 열심히 공부해요. (Propositive)




5. Examples

What you saw in the conjugation rule was only the first part of a sentence. Now, using those 아/어/여서 let's see how whole sentences look alike. Don't forget to make your own sentences!


1

  • 배가 고파서 빵을 먹었어요. I had some bread because I was hungry.


배가 고프다 means "to be hungry". 배 means a stomach and 빵 is bread. You may notice when you translate this 아/어/여서 sentence, you have to say the second part first in English.



2

  • 너무 웃어서 배가 아파요. My stomach hurts because I laughed so hard.


Here is one more example with 배. When a stomach hurts, you can use 배가 아프다. 너무 is an adverb meaning "too, so, or overly." 웃다 is a verb, meaning "laugh." Even though it ends with the final consonant ㅅ, this one is a regular verb! That means it doesn't follow the irregular rules like other "ㅅ" words.



3

  • 젠 씨는 의사라서 바빠요. Jen is busy because she is a doctor.


You can see the conjugation of 이다 with this example. Originally you are supposed to say "의사여서". But in daily conversation "라서" form is more commonly used!



4

  • 눈이 많이 와서 산에 갔어요. I couldn't go to the mountain because it snowed a lot.

  • 눈이 많이 와서 산에 갔어요. I didn't go to the mountain because it snowed a lot.


Can you tell the difference between the two examples above? One is 못 갔어요 the other is 안 갔어요. 못 is an adverb to show can't or couldn't. If you don't have an ability or an opportunity to do the action, you use 못. If you choose not to go, then you can say 안 갔어요.



5

  • 날씨가 시원해서 가을이 좋아요. I like autumn because the weather is cool.


What season do you like? Can you say the sentence with a reason? If you want to know more about the weather and season words, please click here to check!



6

  • 아파서 학교에 안 갔어요. I didn't go to school because I was sick.


아프다 is an adjective. It means "to be sick." You can conjugate an adjective using our target grammar 아/어/여서 like this!




6. Wrap-up & Worksheet: because in Korean

  • To express the reason, you can use the conjunction 그래서 or the connective ending 아/어/여서.

  • You can simply attach 그래서 to the beginning of the second sentence.

  • To use 아/어/여서 to connect two sentences into one, you must conjugate the first verb, adjective, 이다, or 아니다.

  • The key to conjugating 아/어/여서 is the vowel of the last syllable.


It was a big grammar lesson! Please take your time to review it using the worksheet. Conjugating words may seem challenging at first, but if you keep practicing and reviewing, you will be able to speak fluently like a native speaker!


Because in Korean-아어여서-Free Worksheet - My Korean Lesson
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