In this paper, we propose clear-cut definitions of distinct temporal adverbs and provide descriptive features for each class of temporal adverbs. By measuring time points in temporal axis, we revise and reclassify the temporal adverbs listed in [Lu and Ma 1999] into four classes of semantic roles, namely, time, frequency, duration, and time manner. The descriptive features enable us to distinguish temporal relations and predict logical compatibility between temporal adverbs and aspects.