There is a prevalent phenomenon in language that similar meaning can be expressed by different language forms.It is dealt with in the terms of “grammatical
metaphor” by the famous linguist M.A.K.Halliday，including ideational metaphors and interpersonal metaphors.Ideational metaphors are realized by the transference of function of the six processes in the transitivity system.Interpersonal metaphors include metaphors of modality and metaphors of mood.Five standards was first proposed by Halliday and later
the Attic and Doric forms are used to replace the metaphorical and congruent form.The mastery of grammatical metaphor is helpful in English learning，especially in translation and discourse analysis.