Choose the word whose underlined part is pronounced differently

A. Choose the word whose underlined part is pronounced differently.
1.    A. before                    B. report                     C. homework              D. uniform
2.    A. excited                   B. annoyed                 C. pleased                   D. surprised
B. Choose the word that has a different stressed syllable from the rest.
3.    A. classmate               B. finish                     C. essay                      D. abroad
4.    A. difficult                 B. however                 C. positive                  D. chemistry