There are four sentence types including 'u' 'bə' as follows:
1. u+N(p)+bə u+N(p) bə+N(p)
2. u+A(p)+bə u+A(p) bə+A(p)
3. u+V(p)+bə u+V(p) bə+V(p)
4. V+u+bə V+u V+bə
In the first and the fourth types, 'u'・'bə' have no other value than that of a verb pure and simple. But besides being a verb, they are also used as aspect-markers in the second and the third types. There was a mistaken notion of the function of 'u'・'bə' in the third type. They have been thought to be tense-markers by the past writers. 'u'・bə' in the second and the third types have the function of shifting adjective and verbal aspects from punctual nature (taking place at a point of time) to durative nature (extending over a period). The writer has established the grammatical category of aspect in the Fukien dialect by analyzing the sentense types and their tonal sandhi.