Find the word that has different stress from the others. 1. A. permanent B. pollution C. aquatic D. behavior 2. A. substance B. visual C. affect D. billboard 3. A. earplug B. rubbish C. thermal D. beneath 4. A. compliment B. procession C. ancestor D. stepmother 5. A. incense B. spindle C. worship D. reflect 6. A. radiation B. contaminate C. definition D. electricity 7. A. groundwater B. illustrate C. dramatic D. overhead 8. A. obligation B. commemorate C. contaminate D. historian