1. Household and farming chemicals _________ air pollution. A. lead in B. result to C. cause D. causes 2. Thermal pollution _________ the temperature of a river go up. A. makes B. cause C. lead to D. result in 3. Radioactive pollution _______ skin disorders. A. makes B. causes C. leads D. results 4. Forest fires ________ the pollution of the air. A. results in B. causes C. leads to D. lead to 5. What ________ the death of so many fish in the river? A. made B. has cause C. led in D. has result 6. The air has been polluted _________ emissions from car engines. A. since B. because C. because of D. due of 7. Forest fires happen too often, ________ the air is polluted. A. so B. because C. since D. due to 8. Skin disorders happens ________ radioactive pollution. A. because B. due to C. since D. so