English

ต้อง, ได้ ไหม and ไม่ ได้: must, may and must not

"Must" is the familiar ต้อง plus a verb: tong booking hong — "you must book a room". The verb takes no form at all: tong is the only word carrying the obligation. For example: “ต้อง จอง ห้อง” — You must book a room. A rule from the Thai course: worked out on examples, not memorized as a wording.

Updated September 1, 2026 · Lingofly

How it works

"Must" is the familiar ต้อง (тонг) plus a verb: tong booking hong — "you must book a room". The verb takes no form at all: tong is the only word carrying the obligation.

"May I?" — verb plus ได้ ไหม (дай май): chim dai mai — "may I taste?". Dai means "it works, it came off" — permission in Thai is described as possibility. The answer "you may" is simply dai.

"May not" is ไม่ ได้ (май дай): khao mai dai — "no entry". Thai does not separate "not allowed because forbidden" from "it does not work": one mai dai closes both. And "no need" is ไม่ ต้อง (май тонг): mai tong ro — "no need to wait". Mixing up mai dai and mai tong means saying "I am forbidden" instead of "it is optional".

The strict "forbidden" is a separate word, ham: it is written on signs. In live speech it is almost never heard — mai dai is enough.

Table

ต้อง, ได้ ไหม and ไม่ ได้: must, may and must not
MeaningFormulaExampleMeaning
mustต้อง + verbต้อง ไปhave to go
may I?verb + ได้ ไหมชิม ได้ ไหมmay I taste?
may notไม่ ได้เข้า ไม่ ได้no entry
no needไม่ ต้องไม่ ต้อง รอno need to wait
forbiddenห้ามห้าม เข้าentry forbidden

By example

  • ต้อง จอง ห้อง
    тонг джонг хонг
    You must book a room
  • ชิม ได้ ไหม
    чим дай май
    May I have a taste?
  • ไม่ ต้อง รอ
    май тонг ро
    There is no need to wait

How the rule settles in your head

A rule is not memorized from an explanation. It is memorized from an attempt to use it and a mistake — that is why the app delivers it mixed in with words, not as a separate lesson: it resurfaces exactly where you forgot it.

Frequently asked

must, may and must not: how does it work in Thai?

"Must" is the familiar ต้อง plus a verb: tong booking hong — "you must book a room". The verb takes no form at all: tong is the only word carrying the obligation.

What does it look like in a Thai example sentence?

“ต้อง จอง ห้อง” (тонг джонг хонг) — You must book a room. A rule is easier to test on sentences like this than to memorize as a wording: what surfaces in conversation is the sentence.

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Test the rule on examplesPractice