Choose the word whose main stress is placed differently from the others in each group

Choose the word whose main stress is placed differently from the others in each group:
 
1/ A. people B. classmate C. lesson D. devote
 
2/ A. background B. tutor C. degree D. master
 
3/ A. student B. career C. tiny D. research
 
4/ A. passage B. unit C. little D. become
 
5/ A. mother B. mature C. sister D. tragic
 
6/ A. secondary B. impossible C. laboratory D. conditional
 
7/ A. November B. December C. October D. January
 
8/ A. receive B. private C. brother D. children
 
9/ A. general B. condition C. another D. together
 
10/ A. position B. extremely C. continue D. difficult