Present perfect and a finished time

Learning outcome

You can choose present perfect or simple past from the time word, and you can pair since and for with the perfect.

Concepts and reasons

Present perfect is have or has plus the past participle. Use it when a past action still matters now, and the sentence gives no finished clock time. Simple past is for a finished time. Yesterday, ago, last year, and in 2019 are finished times. They take the simple past, not the present perfect. since names the starting point: since 2018, since Monday. for names the length: for five years, for two hours. When the situation is still true, since and for take the present perfect: I have lived here since 2018. I have lived here for five years. I know him since 2018 is wrong. know is present, and since needs the perfect: I have known him since 2018.

Worked examples

1. I have finished the work. No clock time is given, and the result is present. have finished.
2. I finished the work yesterday. yesterday is a finished time, so finished, not have finished.
3. She has lived in Delhi for ten years, and she still lives there. for ten years with a situation that continues takes has lived.

Common traps

Have finished yesterday joins a perfect with a finished time. Drop have, or drop yesterday. Not both. Did you ever go to Agra can be a finished question about a past occasion. Have you ever been to Agra asks about your life up to now, with no date. The exam expects have with ever when no date is given. for and since do not by themselves force the perfect if the time is closed. I lived there for ten years, and then I left, is simple past, because the living has ended. The sentence must show that ending.

Practice questions

1. I ___ him since 2018.
2. She ___ the letter yesterday.
3. They still live here. They ___ here for ten years.

Answers and explanations

1. have known. since plus a situation that continues needs the present perfect. know since is wrong.
2. posted, or wrote. yesterday forces the simple past.
3. have lived. still live tells you the period continues, and for ten years measures it.

Analogy

Present perfect is a light still on from an earlier switch. Simple past is a light you switched off at a named hour. yesterday names the hour, so the light is off. since names when you switched it on, and it is still on.

Quick reference

• No finished clock time, result still present: have or has + participle.
• yesterday, ago, last year, in 2019: simple past.
• since + starting point, for + length, when it still continues: present perfect.
• I have known him since 2018. Not I know him since 2018.