ساختار معنایی افعال وجهی در زبان فارسی امروز

This is a comprehensive research on modality in persian language. All the Grammarians introduced them according their functions in a setence, didn’t pay attention to their meanings.In this essay , their semantic functions was Represented in the relation to discourse. Since they have various meanings,context should help the listener to get the right meanings. Modality allows the speaker classify his / her intention , commitment,… Moreover, they Were represented on a continuum from the most transparent meaning to the most opacity. For example: HAD BETTER(English) BEHTAREH(Persian) 
In this language , behtare proceed a negative verb,such as BEHTAREH NARI The meaning is, you shouldn’t go there, it is a suggestion.Somtimes they have more than one meaning like BAYAD,TAVANESTAN,MOMKEN,KHASTAN,ADATDASHTAN
their meanings were classified regarding Transparency to Opacity. Its goal is to answer the following question “what are the effects and non-Effects of modality upon linguistic structure? We considered the spoken language But it can examined in sign language ,too.Some regards gestures as manual-Visual modality.  As a whole , modality is an important part of a language that relates to discourse factors.The modals can convey the speaker’s intention accompanying the syntactic structures.The inherent meaning of them is transparent ,but other meanings are towards opacity. Transparency and Opacity are semantic concepts but relates to pragmatics.In this situation, Context will help the listener to get the 
speaker’s intention. As a conclusion, the impotant factors in conveying the meaning of modals are as follows: 
1)Focus 
2)context 
3)linguistic segments