Learn Hardcore Korean: pari apaseo mugeoun mulgeoneul mos deureoyo. - My arm hurts, so I can’t lift heavy objects.

The connective ending -아서/어서 attaches to the verb or adjective stem to show reason or cause. Here, 아프- (to hurt/ache) plus -어서 gives 아파서, meaning “because it hurts.” It links the first clause (“my arm hurts”) with the result clause (“I can’t lift heavy things”).

Why is 아파서 used instead of just 아파요?

아파요 simply states “it hurts.” To express “because it hurts, …,” you need the connective form 아파서. Without that connector, you don’t show the causal relationship between the arm hurting and being unable to lift heavy objects.

What part of speech is 아프다, and why doesn’t it need an object?

아프다 is a descriptive verb (often called an adjective in English explanations). Descriptive verbs describe states or qualities and don’t take a direct object. You say 팔이 아파요 (“my arm hurts”) by marking 팔 with the subject particle 이.

What is the function of 을 in 물건을?

The particle 을 marks 물건 as the direct object of the verb 들다 (“to lift”). So 물건을 들어요 means “I lift an object” or “I lift objects.”

Why is it 무거운 물건 instead of 무거운을 물건?

In Korean, adjectives (descriptive verbs) modify nouns directly by taking the noun without any extra particle. 무겁다 (to be heavy) becomes 무거운 to modify 물건 (“thing”), giving 무거운 물건 (“heavy thing”). You don’t add a particle between the adjective and the noun it describes.

What does 못 들어요 mean, and how is it formed?

못 is an adverb meaning “cannot” or “unable to.” It’s placed before the verb (or descriptive verb) to negate ability. 들다 (to lift) in polite present is 들어요, so 못 들어요 means “cannot lift.”

What is the dictionary form of 들어요, and how does it change?

The dictionary (basic) form is 들다.

Polite present affirmative: 들어요
Polite present negative with 못: 못 들어요

This pattern (stem + -어요/-아요) is the standard polite ending in Korean.

Can I replace -아서/어서 with -니까 to mean “because”?

Yes, you can also use -니까 (another “because” connector), but it often feels more direct or somewhat more formal in spoken Korean. You’d say 팔이 아프니까 무거운 물건을 못 들어요. Both sentences are correct, but -아서/어서 is more neutral and commonly used in everyday conversation.