In the premise of following the politeness strategies, business English correspondence writing also needs through some necessary writing skills to reflect the "polite", create atmosphere about respecting each other and seeking cooperation in international business, make each other happy to cooperate, thus occupy a place in the competition. In the writing of business English letter, the most used are positive politeness principle and negative politeness principle. The positive politeness principle is to satisfy the listener's desire to be sure, respect and praise. Negative politeness principle is generally used to save face, put forward the request. From the two aspects of vocabulary and sentences, the author carries out a detailed and specific development of these two principles.

3.1 Vocabulary 

Different words in Business English letters can be used in different language environment, and can better reflect the politeness principle, and the following four kinds of sentence patterns are analyzed.

3.1.1. The Use of Positive, Positive Words or Phrases 

In business letters, positive words such as, glad, appreciate, oblige, thank you, pleased, etc. The use of positive emotion meaning words can make the other person's physical and mental pleasure, and promote the cooperation between the two sides. Specially, in the complaints, dunning, claims and other letters, even if the error is not in, also give affirmation and praise for each other what they do, behaving politely.

For example: 

(1) We are really glad to hear that good news.

(2) It gives us pleasure to receive the samples and catalogs that you send us.

3.1.2 The Use of Modal Verbs 

The use of modal verbs in English often makes the tone of the sentence more relaxed and. Such as would, could, should, may, and euphemism humbly express their demands and suggestions and opinions and establish an atmosphere of equality and friendship, increase each other's psychological advantage, so that the other easy to accept, which is conducive to business talks and to reach their goals. 

For example: 

(1) We appreciate it if you ship 2 days in advance.

(2) We could appreciate it if you could ship 2 days in advance.

In the above example, the second sentence, as a result of the use of the modal verb, the tone of the sentence is more euphemistic than the first sentence, which makes people feel more polite. 

3.1.3 For the Sake of the Other Side about the Principle of "Attitude You"

The expressions of foreign trade English letters are usually indirect and euphemistic, which reflects our respect, tolerance and understanding. Besides, using more personal pronouns, for example: “you” and “your”, which can reflect the principle of "You attitude". 

Compare the following sentences: 

(1) Your active participation in this meeting will be highly admired.

(2) We will highly admire your active participation in this meeting.

Although the first sentence is reasonable, but it does not completely take the other side. This sentential form, "We think", to a certain extent, is self - centered, does not make each other feel that is considered from the point of view of the receiver, and does not put each other's interests in the first place. After all, our purpose is to make the receiver feel respectable and noticed. The second sentence, which regards each other as the center, fully affirms the positive participation of each other, and fully reflects the principles of politeness.

3.1.4 Flexible Use of Hedges 

The use of hedges, aims to enhance or weaken the meaning and tone, to reflect the principles of politeness. In the transfer of positive messages, the use of greatly, very, highly, quite and other hedges can increase the degree of appreciation and praise, reflecting the principle of "praise" and "agree". 

For example: 

(1) We were very pleased to receive your price list of July 7.

(2) Your prompt delivery will be highly appreciated.

In the first sentence, if the "very" is removed, the meaning of the sentence is not changed, but the tone is greatly weakened, and it can not express our feelings of joy and praise each other well. The second sentence，in the similar way, the use of the word “highly” significantly enhances the positive tone of this sentence clearly. Besides, it intensely expresses our side’s gratitude, meanwhile this sentence can implicitly suggest that we look forward to a timely manner from the other side.

In the transmission of negative information, the use of some hedges, such as, I’m afraid, probably, a little bit, it is reported, it seems, I suppose and other hedges, which can slow down tone, and weaken the negative effect. At the same time, showing our intentions, we can not be arbitrary and direct, just to take care of each other's psychological and feelings, as to boosting cooperation. 

For example: 

(1) I am afraid that the price you quoted is not acceptable.

(2) It seems to us that you should have accepted the price.

Using the limit of vague language after in these two sentences, it greatly reduce the tone of rejection and blame, seems modest and euphemistic, and can make them easy to accept, thus achieve the purpose of communication.