The Perfect Progressive in Thai grammar is used to indicate an action that started in the past, continued until a certain point in time, and is still ongoing at the present moment. It is a combination of the Perfect and Progressive aspects.

To form the Perfect Progressive, we begin with the auxiliary verb “ได้” (dâi) which indicates the ability or possibility of doing something. This is followed by the verb “ใช้” (chái) which means “to use” and an action verb in its Progressive aspect form. Lastly, we add the word “มา” (maa) which means “come.”

For example:
– เขาได้ใช้กำลังทำงานมานานแล้ว (kăo dâi chái kamlang tham-ngaan maa naan láew) – He has been using strength to work for a long time already.

In this sentence, “ได้” (dâi) is the auxiliary verb, “ใช้” (chái) is the Progressive verb, and “มา” (maa) indicates that the action has been ongoing until the present moment.

The Perfect Progressive is a useful aspect in Thai grammar as it helps describe actions that have been continuously happening over a period of time.