Exercise 1: Choose the word (A, B,C, D) whose main stress is different from that of the others in each line.1. A. happen B. floppy C. cotton D. decide2. A. reply B. idol C. birthday D. notice3. A. embarrass B. imagine C. careful D. apartment4. A. signature B. appreciate C. attitude D. memorable5. A. comfortable B. constancy C. difficulty D. intelligent6. A. journalist B. humorous C. understand D. beautiful7. A. humorous B. successful C. apartment D. attraction8. A. quality B. rumour C. certain D. concerned9. A. cotton B. happen C. extremely D. quickly10. A. situation B. different C. conservation D. inexpensive