geunyeoga useumyeon nado ttara usge dwae.

I

Breakdown of geunyeoga useumyeon nado ttara usge dwae.

• ~가: subject particle
• ~도: additive particle
• 따라: along

Questions & Answers about geunyeoga useumyeon nado ttara usge dwae.

Why is it 그녀가 and not 그녀는?

가 marks 그녀 as the subject of 웃으면.

So the structure is:

• 그녀가 웃으면 = if/when she smiles/laughs
• 나도 따라 웃게 돼 = I also end up smiling/laughing along

Using 가 is very natural here because it simply identifies who is doing the action in the conditional clause.

If you used 그녀는, it would sound more like setting up she as a topic or contrast, as in as for her, when she smiles... That is possible in some contexts, but 그녀가 is the most straightforward choice here.

What does -으면 mean in 웃으면?

-으면 is a conditional ending meaning if or when.

Here, 웃으면 comes from:

• 웃다 = to smile / to laugh
• 웃으면 = if/when (someone) smiles/laughs

In this sentence, it often feels closer to when or whenever rather than a strict hypothetical if, because it describes a natural repeated reaction:

• 그녀가 웃으면 = when/whenever she smiles

So this sentence can express a general tendency, not just one future event.

Why is it 나도 and not 내가도 or ?