The patterns that quietly mark you as "still learning": for/since, a/an/the, everyday phrasal verbs. Drill them until you can't get them wrong.
- for vs since — "since 2019"
- a, an, the
- "I've just finished" vs "I finished"
- used to — "I used to commute"
- will vs going to — "I'll get it" / "I'm going to quit"
- must, have to, should
- the ways to say "if" — "if I had time, I'd…"
- everyday phrasal verbs (pick up, find out)
- who / which / where — "the colleague who left"
- saying what someone said — "she said she was tired"
+ more — a sample of the full B1 set