oneureun haesbichi ganghaeseo seonkeurimeul kkok ballaya haeyo.

The sunlight is strong today, so I have to put on sunscreen.

Breakdown of oneureun haesbichi ganghaeseo seonkeurimeul kkok ballaya haeyo.

• ~이: subject particle
• ~을: object particle
• ~은: topic particle
• 오늘: today

Questions & Answers about oneureun haesbichi ganghaeseo seonkeurimeul kkok ballaya haeyo.

Why is it 오늘은 and not 오늘이?

은/는 is the topic particle, so 오늘은 means something like as for today or today, ....

In this sentence, 오늘은 sets the scene:

• 오늘은 = today
• then the speaker says what is true today: the sunlight is strong, so you need sunscreen.

If you said 오늘이, it would sound like today is the grammatical subject in a different kind of sentence, which is not what is happening here.

So:

• 오늘은 = topic / setting
• 햇빛이 = subject of the clause that follows

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Why does 햇빛 take 이 in 햇빛이 강해서?

Here, 햇빛이 is the subject of 강하다 (to be strong/intense).

So the structure is:

• 햇빛이 강하다 = the sunlight is strong

The particle 이/가 marks the thing that is doing or being something in the clause. In this sentence, what is strong? 햇빛.

So:

• 오늘은 = topic
• 햇빛이 = subject
• 강해서 = because it is strong

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What does 강해서 mean exactly, and how does -아서/-어서 work here?