Same as the other commercial advertisement, public service advertisement aims to deliver some kinds of information to the public in a short time. The reason why it is so attractive is not only the vocabulary or the grammar, but also the adoption of figures of speech, which implies some new meanings on the original idea that are lively and vivid, in order to leave a deep impression to people. There are some common figures of speech that PSA generally adopts. \
The article will stands on the point of view of rhetoric, discussing the PSA language, and mainly on the application of the figures of speech on PSA.

To some extent, every object in the world exists with its unique characteristics around us. One of the rhetorical expressions, personification is to express lively these unique characteristics by a vision method. Personification regards the static entities as living dynamic entities, also implies some human being characteristics on the static entities. The application of personification is to give lives to the objects,(such as animals, plants) with the fancy imagination, in order to express the inside relationships of the object appropriately. It is a simple, touching rhetorical expressions which drives people generate infinite reverie. It is good to express in a relaxed and humor way, leading a communication between creative people and the public. Personification makes the dull sentences out of the form of sermon, but much closer to the audiences.

Puns plays an important role in making two different meanings of the vocabulary and sentence by using the word with same pronunciation but different meanings or same character but different meanings, which make language more lively and interesting but not sensationalized. English PSA’s layer and richness of the structure are particular effective by using puns makes the easy understanding words become more meaningful. For an instance, the Thailand Population and Community Development Association’s advertising that every pair of couple is only allowed to have two children by using a slogan ‘Stop at two’. And the back cover of the advertisement shows that Churchill posting a ‘V’ gesture with forefinger and middle finger and ‘V’ stands for success. Therefore, people will be thinking in a way that, having two children is success. The photo spreads widely and people now understand the importance of birth control. The organizer of the advertisement uses puns to show his/ her objective easily and meaningfully, leaves a deep impression to the audience. For another example, a safe driving slogan “Better late than the late” is imitating the structure of an English idiom “Better late than never”. It is interesting to point out the dual meanings of the word “late”. “late” stands for being or occurring at an advanced period of time or after a usual or expected time, and we also use “late” when you are talking about someone who is dead, especially someone who has died recently. The slogan is meaningful and imitating the familiar idiom delivers great information to audience. “The drive rise safer when the road is dry; the road is safer when the drive rise dry.” This traffic slogan reminds people “if the road is dry, and the driver doesn’t drink, all the drivers will be much safer.” Here, the “dry” is the pun that refers to the road as well as the drivers. Furthermore, the slogan uses comparison and rhyme in order to make it smoother and memorable.

Comparison is a common phenomenon of the objectives in the world. It reflects a relation of the contrasting objectives very well, as well as the outstanding performance of the technique of expression. It plays a vita role in performing the nature and character of the objectives straightly. By using different kinds of objectives to contrast or compare each other and stand out. The measure of comparison, not only strengthens the power of performance, but also including the interest, maximizes the infection of the advertisement.
For example, “a tree can be made into thousands of matchsticks; a matchstick can ruin thousands of trees.” It is slogan advertising the prevention of bushfire and using the figure comparison, which states the importance of prevention of the bushfire, emphasizes that fire can ruin the forest to a tragedy leading to misbalance of the ecological environment so that keep reminding people to prevent bushfire.

Rhyme is often used by the PSA, alliteration and off-rhyme are the common rhyme methods. Alliteration means the same first-consonant is included in a same term or sentence again and again. And off-rhyme means the same last-consonant is included in a same term or sentence again and again. Slogan uses rhyme can express the idea straightly, simply, explicitly and memorably.
For an instance, “Friends don’t let friends drive drunk.” It is a slogan from American advertising organization as a PSA. “If you drink, you can’t drive.” As another example, the reminder of drunk driving includes the alliteration- “drive” and “drunk” that is catchy and became a popular slogan in America to remind people not to drive after drunk.

Parallelism is a familiar figure of speech to us, it is a parallel structure or parallel construction, is a balance within one or more sentences of similar phrases or clause that have the same grammatical structure. Lots of parallelism sentences are used in PSA that aims to improve the performance of language, maximize the infection of the advertisement in order to attract the consumers.
For example, “I donate my blood, I feel proud of me; I donate my blood, I feel healthy; I donate my blood, I feel happy.” It is slogan advises people to donate their blood for free and using 3 parallelisms. Stating out the adventure of blood donation and triggering more people to make an action and focus.