Language/Thai/Grammar/Tenses
The verb in Thai is invariable.
Time is expressed either by context or by a small word placed before or after the verb.
The present tense
This is the easiest, since the verb is used without any additives.
Since it is invariable, it is used directly:
I'm eating / changin / ฉัน กิน
I'm going / chanpaï / ฉัน ไป
The past tense
The past is marked:
- by the word แล้ว lèo (already) placed after the verb, at the end of the sentence,
- either by the auxilliare ได้ daï always placed before the verb,
- simply by the context of the sentence.
Note: lèo is used if there is no notion of date, contrary to dai.
lèo is never used in negative forms which is logical since it means already.
I ate translates as changinlèo which literally means I am already eating.
if we pass the sentence in negative it becomes:
I did not eat: chanmaïdaïgin
Attention: maïdaï placed after the verb means "cannot":
Changinmaidai = I cannot eat.
For the negative form passed, maïdaï is always in front of the verb.
Here are some examples of past sentences:
I went to school / chanpaïrong rieanlèo / ฉันไปโรงเรียนแล้ว
Yesterday, I went to school / meua wanchanpaïrong riean / เมื่อวานฉันไปโรงเรียน
Here is the context that marks the past.
The future tense
The future is marked by the little word จะ dja, placed in front of the verb.
I will eat / chandjagin / ฉันจะกิน
I will go / chandjapaï / ฉันจะไป
Sources
http://www.thailande-guide.com/zone-thailande/cours-thai-temps.html