If the affirmative form of the present perfect conveys a sense of 'what has been done' from the past until now, the negative form (haven't / hasn't p.p.) is closer to the feeling of filling the 'blank period' that has remained empty since the last action in the past.

To specify the starting point or duration of this blank space, it pairs with since to establish a point of reference and for to indicate the length of the duration.

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1. Continuously since a specific point: since + point in the past

Following since comes an exact starting point in the past, such as Monday, last week, or 2020. It indicates a period where "that day was the last time, and no action has occurred since then."

• I haven’t seen Tom since Monday.
  • Meaning: I have not seen Tom since Monday.
  • Explanation: The last day I saw Tom was Monday (Monday was the last time I saw him), and I have not seen him from Tuesday until now.
• We haven't had a day off since last month.
  • Meaning: We have not had a day off since last month.
  • Explanation: The last time we rested was last month, and we have been working continuously without a break from that time until now.

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2. Throughout a period of time: for + length of time

Following for comes a chunk of time (duration), such as two days, three months, or several years. It denotes the continuation of a state where "the action has been stopped for this long."

• Sarah hasn’t phoned for ages.
  • Meaning: Sarah has not called for a very long time.
  • Explanation: The last time Sarah called was a very long time ago (the last time she phoned was ages ago), and there has been no phone call throughout that long period.
• I haven't played tennis for years.
  • Meaning: I have not played tennis for years.
  • Implication: Several years have passed since I last played tennis, and I have not played a single time during that long period.

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[Summary]

When you are confused about whether to use since or for after a present perfect negative sentence, look at the nature of the word that follows.

• 📌 since + [point in the past] ➔ since Monday / since 2025
• 📌 for + [amount of time] ➔ for two days / for ages

When you want to say, "It's been a long time since I've done that," try thinking of the I haven't done it for... or since... structure instead of struggling with the past tense; this will lead to much more natural expressions.

Today's content is short, but it is very important. Please make sure to review it thoroughly, construct your own sentences, and practice speaking them aloud.

See you in the next Unit 12. Good luck, everyone!