These researches mainly focus on two aspects: one is the status of functional categories in the initial state, the other being the extent to which L2 grammars diverge from the target language in terms of the representation of functional projections.

The paper,based on the theory of grammatical metaphor and tense system in Systemic Functional Grammar(SFG),explores a particular aspect of academic discourse: the English tense of projecting verbs,which is an essential feature of academic discourse.

Therefore,it is significant in theory and in practice to re- search the investment function of the stock market.

The syntactic function is the extension of its morphological function.

Through the analysis of some instances about ellipsis of the functional words in authentic situations,this essay tries to reveal some laws of ellipsis in functional words.