The single grammar mistake that pulls a B1 learner down to B2 is mixing have done and did. The good news: there's one question you ask yourself before every sentence, and it picks the right tense automatically.
The one question that picks the tense
Before you say a verb, ask: "Can I say when this happened?"
- Yes → past simple (did, went, ate)
- No → present perfect (have done, have gone, have eaten)
That's it. The whole system collapses into this one decision.
"I saw him yesterday." (When? Yesterday. → past simple) "I have seen him." (When? Doesn't matter, no time given. → present perfect)
The time-word cheat sheet
Certain time words ALWAYS pair with one tense. Memorize the lists:
Past simple time words (specific, finished moment): yesterday, last week, last year, in 2020, two days ago, at 3pm, when I was a child, on Monday
Present perfect time words (open, unfinished, or unspecified): ever, never, already, yet, just, since 2020, for two years, recently, so far, this week (still going), today (still going)
The "still relevant now" test
When no time word is given, ask: does the result still affect the present?
- "I have lost my keys." → still lost. → present perfect.
- "I lost my keys yesterday." → finished story. → past simple.
The same event can take either tense depending on whether the result still matters NOW.
The classic mistake to never make
The fix is mechanical: see yesterday, last, ago, in [year], when? → past simple. No exceptions.
Practice: pick the right tense
Fill the blank with the correct form (past simple or present perfect):
- I in Tokyo for three years. (still living there now)
- She in Paris in 2018. (specific year — finished)
- sushi? (open question)
- We to the cinema yesterday.
- He the report yet.
- I her since Monday.
- They a new car last week.
- The bus .
Bonus: irregular past participles you'll need
Most past participles end in -ed (worked, finished). But the high-frequency verbs are irregular. Drill these — they're 80% of present-perfect usage:
see(past participle) go(past participle) do(past participle) be(past participle) eat(past participle) give(past participle) take(past participle) write(past participle) break(past participle) speak(past participle) drive(past participle) forget(past participle)If you can recall all 12 in under 10 seconds, you have the pattern. If not, drill them daily for a week.
If you still find yourself mentally translating tense decisions from your first language, the deeper fix is in how to stop translating in your head — the same routing problem that slows down every part of your English.