There are two main tendencies in recent research on verbal 'aspect', one aiming at defining a conceptual aspectual system, independent of each particular language, and the other analyzing aspectual phenonmena in particular languages or in comparison between languages. The former fails in the test of availability while the latter in a general view of the aspectual system as a whole. This paper gives a hypothesis of the conceptual aspectual system and then connects it with various linguistic means of aspectual expressions to test its availability.