Learn Hardcore Korean: i yeonghwaga gamdongjeogieyo.

Both 가/이 and 는/은 mark subjects, but they have different nuances. 이 영화가 (subject marker -가) emphasizes that “this movie” is the thing being felt as moving. If you said 이 영화는 감동적이에요, you’d be introducing or contrasting “this movie” in general, perhaps implying a comparison (“As for this movie, it’s moving, but…”). In most cases where you simply want to point out the subject experiencing the quality, -가 is more natural.

What does the suffix -적 do in 감동적?

The suffix -적 is a Sino-Korean affix that turns a noun into an adjective meaning “related to” or “-ic/-al” in English. Here, 감동 means “emotionally moved” as a noun, and 감동적 means “emotional” or “moving.” It’s equivalent to English turning emotion into emotional.

What part of speech is 감동적이에요, and why does it end in -이에요?

감동적이다 is a descriptive verb (often called an adjectival verb). You remove -다 to attach the polite ending:
• Because the stem ends in a consonant (적), you add -이에요 (consonant + 이에요).
Had it ended in a vowel, you’d use -예요. So 감동적 + 이에요 = 감동적이에요, meaning “is moving/touching.”

How would you change the sentence to past tense (“was moving”)?