as i speak chinese near to a Native level . i can say that Thai don't have the question that you ask: 3 tones + 3 tones first 3 tones Must change to 2 tones, also the word 不 is change too when combined with 3tone and 4 tone. however, as you know Thai tones don't change according to the word following. but Thai, word do change tones in some conditions. all the Thai alphabets devided into 3 group, 1) high tone alphabets 2) medow tone alphabets 3) low tone alphabets so, keep in mind, the 2)group always the same, they can make 5tones in THai, but the 1) and 3) groups alphabets some can't match 5 tones, so the tricky is here, they will not read as the tone appeared. this is conpricated topic, even Many for many thai. but, it is not too hard. take your times :) good luck ，　ｓａｂａｓｉｂｏ

Hi, In Thai, we have 5 tones and it doesn't depend on those combination. It depends on tone mark (กา ก่า ก้า ก๊า ก๋า) Also, the sound of these tone mark can be different. It depends on the consonant. Quite hard right? Sorry for my bad English and hope this helps :)