The number of domestic studies on "variational pragmatics" (Ren Yuxin, Chen Xinren, 2012) is very limited. The research scopes are also relatively limited, which has not yet attracted the attention of more researchers. Therefore, based on this book The Routledge Handbook of Second Language Acquisition and Pragmatics, this paper aims to sort out and summarize the development trend of pragmatics from the meaning, goal and theory of variational pragmatics, and then put forward suggestions for future research.

Idiomatic phrase are one of the lexical units.Many second-language learners showing great enthusiasm for using idiomatic expressions because of the rich cultural factors inherent in them and the vibrant,hilarious language that is close to life-like.However,  the idiomatic terms are so complicated that they frequently cause foreign learners to struggle with learning and comprehending Chinese.With its own advantages, the idea of lexical chunks has the potential to be a game changer in the teaching of idiomatic.

This paper applies Nida's dynamic equivalence theory to the appreciation of Hardy's masterpiece Tess of the D 'Urbervilles, discusses the translation of the meaning and spirit of the source text in terms of dialects, idioms and annotations from the perspective of functional equivalence theory, and further explores whether the spirit and value felt by the readers of the target text is dynamically equivalent to that felt by the readers of the source text. Finally, this paper shows the clever application of this theory and the determination to promote cultural exchange through Tess of the D 'Urbervilles.

The heat collection evaporator was modeled based on equilibrium homogeneous theory, and the Runge-Kutta calculation method was used to analyze and solve the flow in the heat collection evaporator. The influence of environmental factors such as solar irradiance, ambient temperature and wind speed on the variation of refrigerant pressure in two kinds of heat collecting evaporator was analyzed under the set working conditions. The results show that the solar energy irradiance has a great influence on the pressure drop in the tube of serpentine heat collecting evaporator, and the maximum pressure drop of the refrigerant in the tube is 16.3%, minimum pressure drop is 7.8%. However, it has little influence on the pressure drop of the tube sheet evaporator. The maximum pressure drop in the refrigerant tube of the tube sheet evaporator is 4.8%, minimum pressure drop is 1.8%. When the irradiance reaches 800 W/m², the refrigerant in the serpentine-tube evaporator has been completely vaporized at 6 m, it’s completely vaporized at 3 m.