II.Choose the word whose main stress is placed differently from the others in each group: 1/A. headmaster B. holiday C. attractive D. internet 2/A. matter B. happen C. listen D. below 3/A. explain B. problem C. study D. worry 4/A. habit B. become C. learner D. mother 5/A. fifteen B. fifty C. center D. biggest 6/A. student B. member C. prefer D. teacher 7/A. subject B. hello C. teacher D. thousand 8/A. lesson B. woman C. repair D. father 9/A. above B. sister C. widen D. very 10/A. corner B. answer C. doctor D. prepare