Common English grammar mistakes Thai learners make (and how to fix them)

Why these mistakes happen (it's not you)

Thai and English build sentences differently, so when you speak or write English fast, your brain borrows Thai habits. Thai nouns and verbs don't change form, there are no articles like a/an/the, and 'to be' works differently — so English endings and little words get lost. These are 'first-language interference' errors, and almost every Thai learner makes the same handful.

The good news: because they're predictable, they're fixable. You don't need to relearn English — you need to notice a small number of patterns and drill them until the correct version feels normal. Below are the big ones, with the fix for each.

1. Missing or wrong articles (a / an / the)

Thai has no articles, so they're easy to drop: 'I am student' or 'I saw dog'. English needs 'a/an' for one non-specific countable thing, and 'the' when it's specific or already known.

Fix: say 'I am a student' and 'I saw a dog', then 'The dog was big' once it's known. A quick rule of thumb — a singular countable noun almost always needs a word in front of it (a, an, the, my, this…). If there's nothing there, check it.

2. Dropped plural -s, past -ed, and third-person -s

Thai words don't change form, so English endings get left off: 'three book', 'I walk yesterday', 'she like coffee'. The meaning is clear, but the missing letters cost you marks and sound non-native.

Fix: train three endings until they're automatic — plural -s (two books), past -ed (I walked yesterday), and third-person -s (she likes coffee). When you write, do one quick pass just checking these three endings.

3. Tense slips (especially the past)

Because Thai marks time with extra words rather than by changing the verb, learners often stay in the present: 'Last week I go to Chiang Mai'. English changes the verb itself.

Fix: match the verb to the time word. 'Last week', 'yesterday' and 'ago' need past tense (went, saw, ate). Learn the common irregular verbs (go→went, eat→ate, buy→bought) as a set, because they don't follow the -ed rule.

4. 'To be' with adjectives — added or dropped

Two opposite errors show up here. Sometimes 'to be' is dropped: 'She beautiful', 'I very tired'. Sometimes it's doubled with another verb: 'I am agree', 'He is work here'.

Fix: use 'be' with an adjective (She is beautiful, I am tired), but not with an ordinary verb (I agree — not 'I am agree'; He works here — not 'He is work here'). If there's already an action verb, you usually don't need 'is/am/are' as well.

5. Prepositions and a few classic word choices

Prepositions rarely map one-to-one between languages, so 'in/on/at' and 'depend on', 'good at', 'interested in' have to be learned as fixed pairs. Thai learners also often mix up 'much/many', 'since/for', and countable vs uncountable ('informations', 'advices').

Fix: learn prepositions as whole chunks, not single words — 'arrive at the airport', 'good at English', 'on Monday', 'in July'. For uncountable nouns (information, advice, furniture, equipment), never add -s and use 'much', not 'many'.

• Time: at 7 o'clock, on Monday, in July — small words, fixed patterns.
• Fixed pairs: depend on, good at, interested in, listen to.
• Uncountable: information, advice, news, furniture — no -s, use 'much'.
• many (countable: many books) vs much (uncountable: much time).

The fastest way to fix grammar: drill it, don't just read it

You already 'know' most of these rules — the problem is producing the correct form automatically under time pressure. That's a habit, and habits are built by doing many short, corrected reps, not by re-reading explanations.

engforedu.com/drills is a free bank of 1,500+ grammar and word-choice questions that mark themselves instantly, so you find out the moment you slip and fix the pattern on the spot. Do a few sets a day, focused on the endings and articles above, and the right version starts coming out without thinking. When you want to apply it in full essays with feedback, free practice at engforedu.com/journey scores your writing against the official criteria.