Question Words

The word dâay (ได้) : can, able to, possible to (used at the end of a statement when you want to indicate the ability or possibility of whatever you just said)
So dâay-mǎi (ได้–ไหม) is a question like ‘Can……?’ or ‘Could……?’ but in Thai the question word is placed at the end of the statement.

It is a compound question word combined from dâay (ได้) = can, able to, possible to’ and mǎi (ไหม) = yes/no question word.
Here are some examples:

…………………………. + dâay-mǎi (ได้ไหม)?
Is the subject able to do something? (In ability and possibility)

Question:	khun phûut phaa-săa Thai dâay-mǎi?
	คุณพูดภาษาไทยได้ไหม
	Can you speak Thai?
Answer:	√ dâay	× mâi-dâay
	(ได้)	(ไม่ได้)
	I can.	I cannot.

Question:	chaaw-dtàaŋ-châat sɯ́ɯ bâan thîî bprà-thêet Thai dâay mǎi?
	ชาวต่างชาติซื้อบ้านที่ประเทศไทยได้ไหม
	Can foreigners buy houses in Thailand? [is it possible?]
Answer:	√ dâay khà
	(ได้ค่ะ)
	Yes, (they) can.
	× mâi-dâay khà, dtɛ̀ɛ chaaw-dtàaŋ-châat sɯ́ɯ Condominium dâay
	(ไม่ได้ค่ะ แต่ชาวต่างชาติซื้อคอนโดมิเนียมได้)
	No, (they) cannot. But (they) can buy condominiums.

2. The word phen (เป็น): means “able to” in the sense of performing a skill or something which is learned, or about something according to the “rule/law” Something like, “Is the subject able to do something?” where mâi-bpen (ไม่เป็น) would indicate that the subject is not capable of doing that thing.

Here are some examples:

…………………………. + bpen-mǎi (เป็นไหม.?
Is the subject able to do something? (focus on existing ability/skill)

Question:	khun wâay-náam bpen mǎi?
	คุณว่ายน้ำเป็นไหม
	Can you swim? (Do you know how to swim?)
Answer:	√ bpen	× mâi bpen
	(เป็น)	(ไม่เป็น)
	Yes, I can.	No, I can’t.

Question:	khun bpai Central World bpen mǎi?
	คุณไปเซ็นทรัลเวิร์ดเป็นไหม
	Can you go to Central World? [Are you able to get to Central World?’] (Do you know the way to go to Central world? = to know the direction or how to get there.)
Answer:	√ bpen khráp
	(เป็นครับ)
	I can. (I know the way there/how to get there.)
	× mâi bpen khráp
	(ไม่เป็นครับ)
	I can’t. (I don’t know the way/how to get there.)

Question:	khun sà-màk E-mail bpen mǎi?
	คุณสมัครอีเมล์เป็นไหม
	Can you create an email account? (Do you know how to create an email account?)
Answer:	√ bpen khráp… phǒm khəəy sà-màk hâi phɯ̂an
	(เป็นครับ ผมเคยสมัครให้เพื่อน)
	Yes, I can. I’ve done it for a friend before. (I know how to create an account.)
	× mâi bpen khráp
	(ไม่เป็นครับ)
	No, I can’t. (I don’t know how to create an account.)

3. The word wăi (ไหว): used when there’s an expectation that one may not be able to do something, usually due to physical limitations. For instance, a child lifting heavy things or a patient walking on his own–it’s uncertain whether they will be capable of doing that thing. So mâi-wăi (ไม่ไหว) means one is incapable (due to a physical limitation like not being strong enough).

Here are some examples:

…………………………. + wăi-mǎi (ไหวไหม)?
Can the subject handle doing something?

Question:	khun tham-ŋaan 10 chûa-mooŋ wăi-măi?
	คุณทำงาน 10 ชั่วโมงไหวไหม
	Can you work for 10 hours straight?
Answer:	√ wăi khráp	× mâi-wăi khráp
	(ไหวครับ)	(ไม่ไหวครับ)
	Yes, I can.	No, I can’t.

Question:	khun bpuàt hŭa mâak, thâa mâi-wǎi gɔ̂ɔ glàp bâan dâay ná khráp [THIS SENTENCE IS LIKE A QUESTION (wăi-mǎi) SO THE ANSWERS BELOW MAKE SENSE IN THAI.]
	คุณปวดหัวมาก ถ้าไม่ไหวก็กลับบ้านได้นะครับ
	You have a bad headache: if it’s too much you can go home for the day (and get some rest).
Answer:	√ wăi khráp
	(ไหวครับ)
	Yes, I can. [It’s ok, I can keep working.]
	× mâi-wăi khráp
	(ไม่ไหวครับ)
	No, I can’t. [It’s too much; I can’t work anymore today.]

picture from https://www.churchtimes.co.uk/regulars/out-of-the-question