For Professor Lv Hefa, public sign is a peculiar language for helping the public。 It is so quiet sharp and clear that people can get information from it and know the limitation of behavior (8)。 

Given all that, public signs mean the words show to public in the public places, is the most common practical in everyday life in order to achieve a certain communicative purpose as a special text。 They are like silent artificial service working there day and night to help people。 

When public signs meet the public, it can express notices, tips, instructions, display, warning, marking, explanations, production。 The public signs have some similar application characteristics, but the public signs are more widely。

Public signs are an important part of the social language。 Public signs influence people’s daily life and work。 Public signs can standard the movement of people and adjust interpersonal relationships。 What’s more, it can increase production efficiency and reduce crime to inspire enthusiasm, improve quality of life and build a harmonious social environment。

2。2 The Classification of Public Signs

The application of public signs is very extensive。 The information expressed by the public signs in different positions is different, some are telling people the information they need, such as giving directions; some are leading people to do a specific thing, such as a warning。 In this sense, the public signs can be pided into two kinds: static ones and dynamic ones。 

Static public signs are widely used in tourist attractions, supermarkets, roads, hospital, company, etc。 to highlight the function of service and indication。 Here are some examples: 皇家天文台售票处 Ticket for Royal Observatory; 王府井大街 Wangfujing Street; 留学生公寓 International Students House; 环保木材 Forest-Friendly Building Timbers。

The static public signs give people effective information to know the surrounding environment and never feel helpless。 It reflects attentive information service without any limitative or compulsive meaning。 The application of language does not require people to take action and its functions indicate the content of service。 

Opposite to the static public signs, dynamic ones deliver information in a dynamic state。 Public signs of this kind are usually with tough tone, containing the meaning of requirements and restriction。 Its purpose is to attract the public’s attention so as to achieve its objective。 It is widely used in public traffic system, public places。 Here are some examples: 请在乘车前购买好车票 Please buy your ticket before you board the train; 为避免拥堵，请勿在楼梯附近停留 To avoid congestion, please do not stand near the stairs; 立即行动，保护自然 Act now, save what’s left; 行李舱必须关闭 Bins must be closed。 People must observe the requirements of public signs。 文献综述

The study of static signs and dynamic signs can help people to analyze and grasp the public signs better and translate it more effectively so as to convey accurate information to the public。 Generally speaking, dynamic public signs make a direct impact on the visitors whereas the static public signs make an indirect but lasting impact on the visitors。 So the combination of static and dynamic public signs in the public places could satisfy people’s demands for the information。 

2。3 Functions of Public Signs 

With the acceleration of the process of China’s reform and opening up, especially after China joined the world trade organization, China has become more and more frequent exchanges with the word。 At the same time, English is using frequently as an international language in China。 But in daily life, there are many errors in English translation, the most obvious is the public sings。 The C-E placards are set up universally in main public places not only in large cities but also in some medium cities such as railway stations, airports, shopping malls and scenic spots。 They are mainly set up in the form of bilingual signs to convey instructions, achieve information intention of reminding, requesting and warning so as to supply convenience for foreign guests。 Bilingual signs are becoming more and more normative, standard and proper due to the efforts from all trades and professions。 They play an important role which translators must pay more attention to external publicity (Chen 110)。 The differences among the functions of public signs result in the differences between the language styles and moods in English translation of public signs。 Different people have different views on the classification of public signs。 According to the classification of Professor Lv Hefa, public signs have four basic functions, they are: directing, prompting, restricting and compelling (8)。