Topologically Transitive Continuous Semi-flow Chaotic Nature

In this paper, we study the sensitivity and the topological property of periodic points for topologically transitive semi-flows on a mertic space. In details, we prove the following results: (l)a topologically transitive semi-flow is either sensitively dependent or uniformly rigid, it follows that only topologically transitive semi-flow(which is not a flow), is sensitively dependent; (2)if a topologically transitive semi-flow is not minimal and there is an invariant probability measure whose support is the whole space, then it must be sensitively dependent; (3)a semi-flow,which is chaotic in the sense of Devaney, has a dense set of large-periodic points.