써서

In a sentence

• 나는 펜을 써서 편지를 썼다.

  I wrote a letter using a pen.

  Here, '써서' is used to denote the means or tool used to complete an action.

• 그는 약속을 지키지 않고 변명을 써서 사과했다.

  He apologized using an excuse without keeping his promise.

  Here, '써서' is used to indicate a method or approach of performing an action.

• 그녀는 시간을 써서 자신의 꿈을 이루었다.

  She achieved her dream by dedicating her time to it.

  Here, '써서' shows the use of a resource (time) to achieve an outcome.