2。3 TED Speeches 

TED is short for Technology, Entertainment, and Design。 It is a worldwide set of conferences conducted by a private non-profit organization----Sapling Foundation in 1984。 The aim of TED is to disseminate “ideas worth spreading”。 

The annual conference is held in Long Beach and its companion TED Active is held in Palm Springs。 In 2014，both conferences moved from Long Beach and Palm Springs to Vancouver and Whistler respectively。 TED events offer live streaming of the talks which are held throughout the United States and in Asia and Europe。 Since then the influence of TED speeches has been increasing。 

TED conference invites the world’s captivating thinkers and doers no matter which country they come from or which language they speak to deliver speeches about their experiences and ideas。 The topics they address cover a wide range in culture and science。 The speakers are given at most 18 minutes to deliver their speech in the most engaging and innovative ways they can。 

The talks have been free for viewing online through TED。com since June 2006。 The TED conference had been watched more than 50 million times by January 2009。 The viewing figure was more than 500 million in June 2011, and TED Talks had been viewed one billion times throughout the world on November 13, 2012, which reflects a forever growing global audience。 

In May 2009, TED Open Translation Project started and according to TED Curator Chris Anderson, it is formed to “reach out to the 4。5 billion people on the planet who don’t speak English”。 The OTP utilizes crowd-based video subtitling and captioning platforms to translate the text of TED videos。 

300 translations had been done by 200 volunteer translators in 40 languages at the time of the launch。 More than 32700 translations had been completed by 8382 volunteer transcribers in 93 languages in December 2012。 There are 377 videos with culture tag and 47 videos with communication tag up in TED website Until January 12th 2012。

III。 Theoretical Framework: Pragmatic Presupposition

3。1 Semantic Presupposition 

Strawson (1952) gave the definition of semantic presupposition as “A statement S presupposes a statement S’ if and only if the truth of S’ is necessary condition for the truth or falsity of S”。 Fasold (2000) defined semantic presupposition as the following: “a relation between what is actually said (or may be said) and something else that has to be the case in order for the thing said to make any sense at all。” For example, 

a。 This person is a bachelor。 

b。 This person is a man。   

In the example, we can not necessarily get (a) from (b), but we can get (b) from (a)。 If (b) is false, (a) is false; If (a) is true, (b) is true; If (a) is false, (b) could be either true or false, which means that this person is a man who had been married, and this person may be a man or a woman。 

3。2 Presupposition Triggers 

Yule introduces that “in the analysis of how speaker’s assumptions are typically expressed, presupposition has been associated with the use of a large number of words, phrases, and structures。 We consider these linguistic forms here as indicators of potential presupposition”。 These indicators are called presupposition triggers。 (Yule, 2000:67)。 

Levinson selected twelve types of presupposition triggers in his work as the following (Levinson, 1983:105):