Same mistake, different viewpoint:

“I’ve forgotten my keys.” → The problem matters NOW. You’re outside; the keys are inside.

“I couldn’t get in because I had forgotten my keys.” → The forgetting happened BEFORE a past moment.

Present perfect: have/has + past participle.
Past perfect: had + past participle.

Pizza version:
“I’ve eaten the last slice.” → No pizza now.
“Before you opened the fridge, I had eaten it.” → Eating came first. Your disappointment came later.

A grammar guide from LingvoBerry. Read the full article for more everyday examples and a quick practice.

https://lingvoberry.com/grammar/en?utm_source=telegram&utm_medium=social&utm_campaign=evergreen&utm_content=post_1

Ben usually works hard. But right now, he’s watching cat videos. The cat is in a tiny box; Ben’s report is in another window. 🐈

• “He usually works hard.” Present simple = a habit.
• “He’s watching a video.” Present continuous = an activity now.

Continuous also covers around now: “He’s working on a report this week.” He may be taking a break when you say it.

Form: am/is/are + verb-ing.

Try: Ben usually ___ emails, but now he ___ a video. (answer / watch)
Answer: answers / is watching.

Takeaway: picture the usual routine, then the current activity.

https://lingvoberry.com/grammar/en/course/a2/present-simple-vs-continuous?utm_source=telegram&utm_medium=social&utm_campaign=evergreen&utm_content=post_2