I . Phonetics( 5 points)Directions:In each of the following groups of words, there are four underlined letters or letter combinations marked A, B, C and D. Compare the underlined parts and identify the one that is different from the others in pronunciation. Mark your answer by blackening the corresponding letter on the Answer Sheet.1.( )
A、cake
B、gas
C、bag
D、tax
18. _____the result of the exam, she stood at the door of the classroom,disappointed.