Tenses (Units 1 ~ 8)

시제:

    단순   진행   완료   완료진행
현재 I do I am doing I have done I have been doing
과거 I did I did I had done I had been doing
미래 I will do I will be doing I will have done I will have been doing

Present Simple / Continuous / Prefect / Perfect Continuous
Past Simple / Continuous / Prefect / Perfect Continuous
Future Simple / Continuous / Prefect / Perfect Continuous