【正确答案】A presupposition trigger is a lexical item or linguistic construction which is responsible for the presupposition.
   In the sentence (1), the verb phrase "gave up" triggers inference that Peter had been smoking. This type of presupposition trigger is called "Change of state verbs".
   In the sentence (2), the cleft sentence "What was the most unbelievable was that", triggers inference about the presupposed information is that something great Jack had done. This type of presupposition trigger is called "Cleft sentences".
   In the sentence (3), the verb "charge" triggers inference that Mary thinks theft is bad, and this kind of trigger is called "Verbs of judging".
   In the sentence (4), the word "Before" triggers inference that I had stayed in Beijing for 10 days, and this kind of presupposition trigger is called "Adverbial clauses of time".
   In the sentence (5), the verb "rewrite" triggers inference that the teacher had asked the students to write their compositions on the importance of the Internet before. This presupposition trigger belongs to "iteratives".
   Types of presupposition triggers can trigger cancelable presupposition: Change of state verbs, and Verbs of judging, and Implicative verbs, for example, John stopped beating his wife and from this sentence we can know that John had been beating his wife. This is the case of Change of state verbs, and another Implicative example: I forgot to bring the book. This utterance implied that I ought to bring the books.
   (本题主要考查预设和预设触发语的分类。)