sentence: Suddenly , I thought my gift was gone . The students said they did n't take it , but I doubted them , so we quarrelled .
modified: Suddenly , I thought of my gift was gone in the class , the students said he / she did n't take , but I doubt them , so we quarrel .
transformation: PREP, OTHER, OTHER, PRON, VERB:TENSE, VERB:TENSE