Directions:In each of the following groups of words,there are four underlined letters or let-ter combinations marked A,B,C and D.Compare the underlined parts and iden-tdtify the one that is different from the others in pronunciation.Mark your answer by blackening the corresponding letter on the Answer Sheet.
A、pension
B、mission
C、tension
D、revision
17.The employees___more enthusiastic about their work since their pay rose.
A、are
B、have been
C、were
D、will be
15.At such a time of crisis, we must try __ to all differences and stick together,