Common English Grammar Mistakes (and How to Fix Them)

Most English mistakes are about small words, not big ideas. The same pairs cause problems for learners from many different languages. Learn the short rule for each pair below, then practise it with a quick game, because grammar becomes natural through repetition, not through reading rules.

A or an

Use an before a vowel sound, not just a vowel letter. We say "an hour" (the h is silent) but "a university" (it starts with a "y" sound). Practise A or An →

In or on

Use in for months, years and long periods (in May, in 2026), and on for days and dates (on Monday, on 5 May). Practise In or On →

For or since

Use for with an amount of time (for three years) and since with a starting point (since 2023). Both are common with the present perfect: "I have lived here for three years" and "I have lived here since 2023". Practise For or Since →

Much or many

Use many with things you can count (many books) and much with things you cannot (much water). In everyday speech, we often use "a lot of" in positive sentences. Practise Much or Many →

Some or any

Use some in positive sentences ("I have some milk") and any in negatives and most questions ("I don't have any milk", "Do you have any milk?"). Practise Some or Any →

Simple or continuous

Use the present simple for habits and facts ("I work in a bank") and the present continuous for things happening now or around now ("I am working from home today"). Practise Simple or Continuous →

How to practise

• Pick one pair a day, not all of them.
• Read the rule once, then play the game. Each question explains the rule after you answer.
• Come back to the pairs you got wrong in a few days.

All the pairs are in one place. See every English grammar game →