because the conference lasted two days on the weekend, all participants could attend on each day
without disrupting their work.

위 문장에서 attned 동사가 ~에 참석하다라는 3타동사로 쓰인 것 같은데 어찌 목적어가 없는건가요 ㅠㅠ

궁금해요 궁금해 ㅠㅠ 알려주세요ㅎ;;