YOU SAID:
the party was boring and i left early
INTO JAPANESE
パーティーは退屈だったし、私は早く出発した
BACK INTO ENGLISH
The party was boring and I left early.
INTO JAPANESE
パーティーは退屈で、私は早く出発しました。
BACK INTO ENGLISH
The party was boring and I left early.
You've done this before, haven't you.